Merge pull request #39356 from justinmk/release

backports

4 files changed, 239 insertions, 88 deletions

diff --git a/runtime/lua/vim/lsp/rpc.lua b/runtime/lua/vim/lsp/rpc.lua
index 1cc5ffef44..761c0aac17 100644
--- a/runtime/lua/vim/lsp/rpc.lua
+++ b/runtime/lua/vim/lsp/rpc.lua
@@ -380,7 +380,9 @@ function Client:handle_body(body)
 
   if type(decoded) ~= 'table' then
     self:on_error(M.client_errors.INVALID_SERVER_MESSAGE, decoded)
-  elseif type(decoded.method) == 'string' and decoded.id then
+  elseif type(decoded.method) == 'string' and decoded.id and decoded.id ~= vim.NIL then
+    local id_type = type(decoded.id)
+    assert(id_type == 'number' or id_type == 'string', 'Request id must be a number or a string')
     local err --- @type lsp.ResponseError?
     -- Schedule here so that the users functions don't trigger an error and
     -- we can still use the result.
@@ -426,6 +428,7 @@ function Client:handle_body(body)
   -- - If 'result' is nil, then 'error' must be present (and not vim.NIL).
   elseif
     decoded.id
+    and decoded.id ~= vim.NIL
     and (
       (decoded.error == nil and decoded.result ~= nil)
       or (decoded.result == nil and decoded.error ~= nil and decoded.error ~= vim.NIL)
@@ -477,6 +480,9 @@ function Client:handle_body(body)
       self:on_error(M.client_errors.NO_RESULT_CALLBACK_FOUND, decoded)
       log.error('No callback found for server response id ' .. result_id)
     end
+  elseif decoded.id == vim.NIL then
+    log.warn('Server sent response with null id', decoded.error)
+    self:on_error(M.client_errors.INVALID_SERVER_MESSAGE, decoded)
   elseif type(decoded.method) == 'string' then
     -- Notification
     self:try_call(
diff --git a/test/functional/ex_cmds/trust_spec.lua b/test/functional/ex_cmds/trust_spec.lua
index 5b6210bd3c..8cfb276706 100644
--- a/test/functional/ex_cmds/trust_spec.lua
+++ b/test/functional/ex_cmds/trust_spec.lua
@@ -6,7 +6,6 @@ local clear = n.clear
 local command = n.command
 local exec_capture = n.exec_capture
 local matches = t.matches
-local pathsep = n.get_pathsep()
 local is_os = t.is_os
 local fn = n.fn
 
@@ -15,7 +14,7 @@ describe(':trust', function()
   local test_file = 'Xtest_functional_ex_cmds_trust'
 
   before_each(function()
-    n.mkdir_p(xstate .. pathsep .. (is_os('win') and 'nvim-data' or 'nvim'))
+    n.mkdir_p(vim.fs.joinpath(xstate, is_os('win') and 'nvim-data' or 'nvim'))
     t.write_file(test_file, 'test')
     clear { env = { XDG_STATE_HOME = xstate } }
   end)
@@ -30,10 +29,22 @@ describe(':trust', function()
     return s:format(test_file)
   end
 
+  --- Joins path components using the OS-native separator.
+  --- Unlike vim.fs.joinpath (which normalizes to "/"), this preserves "\" on Windows
+  --- to match paths stored in the trust database.
+  local function osjoin(...)
+    return (table.concat({ ... }, n.get_pathsep()))
+  end
+
+  local function assert_trust_entry(expected)
+    local trust = t.read_file(vim.fs.joinpath(fn.stdpath('state'), 'trust'))
+    eq(expected, vim.trim(trust))
+  end
+
   it('is not executed when inside false condition', function()
     command(fmt('edit %s'))
     eq('', exec_capture('if 0 | trust | endif'))
-    eq(nil, vim.uv.fs_stat(fn.stdpath('state') .. pathsep .. 'trust'))
+    eq(nil, vim.uv.fs_stat(vim.fs.joinpath(fn.stdpath('state'), 'trust')))
   end)
 
   it('trust then deny then remove a file using current buffer', function()
@@ -42,16 +53,13 @@ describe(':trust', function()
 
     command(fmt('edit %s'))
     matches(fmt('^Allowed in trust database%%: ".*%s"$'), exec_capture('trust'))
-    local trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format('%s %s', hash, cwd .. pathsep .. test_file), vim.trim(trust))
+    assert_trust_entry(('%s %s'):format(hash, osjoin(cwd, test_file)))
 
     matches(fmt('^Denied in trust database%%: ".*%s"$'), exec_capture('trust ++deny'))
-    trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format('! %s', cwd .. pathsep .. test_file), vim.trim(trust))
+    assert_trust_entry(('! %s'):format(osjoin(cwd, test_file)))
 
     matches(fmt('^Removed from trust database%%: ".*%s"$'), exec_capture('trust ++remove'))
-    trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format(''), vim.trim(trust))
+    assert_trust_entry('')
   end)
 
   it('deny then trust then remove a file using current buffer', function()
@@ -60,27 +68,22 @@ describe(':trust', function()
 
     command(fmt('edit %s'))
     matches(fmt('^Denied in trust database%%: ".*%s"$'), exec_capture('trust ++deny'))
-    local trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format('! %s', cwd .. pathsep .. test_file), vim.trim(trust))
+    assert_trust_entry(('! %s'):format(osjoin(cwd, test_file)))
 
     matches(fmt('^Allowed in trust database%%: ".*%s"$'), exec_capture('trust'))
-    trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format('%s %s', hash, cwd .. pathsep .. test_file), vim.trim(trust))
+    assert_trust_entry(('%s %s'):format(hash, osjoin(cwd, test_file)))
 
     matches(fmt('^Removed from trust database%%: ".*%s"$'), exec_capture('trust ++remove'))
-    trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format(''), vim.trim(trust))
+    assert_trust_entry('')
   end)
 
   it('deny then remove a file using file path', function()
     local cwd = fn.getcwd()
 
     matches(fmt('^Denied in trust database%%: ".*%s"$'), exec_capture(fmt('trust ++deny %s')))
-    local trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format('! %s', cwd .. pathsep .. test_file), vim.trim(trust))
+    assert_trust_entry(('! %s'):format(osjoin(cwd, test_file)))
 
     matches(fmt('^Removed from trust database%%: ".*%s"$'), exec_capture(fmt('trust ++remove %s')))
-    trust = t.read_file(fn.stdpath('state') .. pathsep .. 'trust')
-    eq(string.format(''), vim.trim(trust))
+    assert_trust_entry('')
   end)
 end)
diff --git a/test/functional/lua/secure_spec.lua b/test/functional/lua/secure_spec.lua
index c7cb1005fd..c68637f00a 100644
--- a/test/functional/lua/secure_spec.lua
+++ b/test/functional/lua/secure_spec.lua
@@ -5,7 +5,6 @@ local Screen = require('test.functional.ui.screen')
 local eq = t.eq
 local clear = n.clear
 local command = n.command
-local pathsep = n.get_pathsep()
 local is_os = t.is_os
 local api = n.api
 local exec_lua = n.exec_lua
@@ -18,13 +17,25 @@ local matches = t.matches
 local read_file = t.read_file
 
 describe('vim.secure', function()
+  --- Joins path components using the OS-native separator.
+  --- Unlike vim.fs.joinpath (which normalizes to "/"), this preserves "\" on Windows
+  --- to match paths stored in the trust database.
+  local function osjoin(...)
+    return (table.concat({ ... }, n.get_pathsep()))
+  end
+
+  local function assert_trust_entry(expected)
+    local trust = assert(read_file(vim.fs.joinpath(stdpath('state'), 'trust')))
+    eq(expected, vim.trim(trust))
+  end
+
   describe('read()', function()
     local xstate = 'Xstate_lua_secure'
     local screen ---@type test.functional.ui.screen
 
     before_each(function()
       clear { env = { XDG_STATE_HOME = xstate } }
-      n.mkdir_p(xstate .. pathsep .. (is_os('win') and 'nvim-data' or 'nvim'))
+      n.mkdir_p(vim.fs.joinpath(xstate, is_os('win') and 'nvim-data' or 'nvim'))
 
       t.mkdir('Xdir')
       t.mkdir('Xdir/Xsubdir')
@@ -56,7 +67,7 @@ describe('vim.secure', function()
 
       local cwd = fn.getcwd()
       local msg = 'exrc: Found untrusted code. To enable it, choose (v)iew then run `:trust`:'
-      local path = ('%s%sXfile'):format(cwd, pathsep)
+      local path = osjoin(cwd, 'Xfile')
 
       -- Need to use feed_command instead of exec_lua because of the confirmation prompt
       feed_command([[lua vim.secure.read('Xfile')]])
@@ -76,11 +87,10 @@ describe('vim.secure', function()
         {MATCH: +}|
       ]])
 
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', cwd .. pathsep .. 'Xfile'), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(osjoin(cwd, 'Xfile')))
       eq(vim.NIL, exec_lua([[return vim.secure.read('Xfile')]]))
 
-      os.remove(stdpath('state') .. pathsep .. 'trust')
+      os.remove(vim.fs.joinpath(stdpath('state'), 'trust'))
 
       feed_command([[lua vim.secure.read('Xfile')]])
       screen:expect([[
@@ -97,21 +107,20 @@ describe('vim.secure', function()
       screen:expect([[
         ^let g:foobar = 42{MATCH: +}|
         {1:~{MATCH: +}}|*2
-        {2:]] .. fn.fnamemodify(cwd, ':~') .. pathsep .. [[Xfile [RO]{MATCH: +}}|
+        {2:]] .. osjoin(fn.fnamemodify(cwd, ':~'), 'Xfile') .. [[ [RO]{MATCH: +}}|
         {MATCH: +}|
         {1:~{MATCH: +}}|
         {4:[No Name]{MATCH: +}}|
-        Allowed in trust database: "]] .. cwd .. pathsep .. [[Xfile"{MATCH: +}|
+        Allowed in trust database: "]] .. osjoin(cwd, 'Xfile') .. [["{MATCH: +}|
       ]])
       -- close the split for the next test below.
       feed(':q<CR>')
 
       local hash = fn.sha256(assert(read_file('Xfile')))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', hash, cwd .. pathsep .. 'Xfile'), vim.trim(trust))
+      assert_trust_entry(('%s %s'):format(hash, osjoin(cwd, 'Xfile')))
       eq('let g:foobar = 42\n', exec_lua([[return vim.secure.read('Xfile')]]))
 
-      os.remove(stdpath('state') .. pathsep .. 'trust')
+      os.remove(vim.fs.joinpath(stdpath('state'), 'trust'))
 
       feed_command([[lua vim.secure.read('Xfile')]])
       screen:expect([[
@@ -131,7 +140,7 @@ describe('vim.secure', function()
       ]])
 
       -- Trust database is not updated
-      eq(nil, read_file(stdpath('state') .. pathsep .. 'trust'))
+      eq(nil, read_file(vim.fs.joinpath(stdpath('state'), 'trust')))
 
       feed_command([[lua vim.secure.read('Xfile')]])
       screen:expect([[
@@ -147,7 +156,7 @@ describe('vim.secure', function()
       screen:expect([[
         ^let g:foobar = 42{MATCH: +}|
         {1:~{MATCH: +}}|*2
-        {2:]] .. fn.fnamemodify(cwd, ':~') .. pathsep .. [[Xfile [RO]{MATCH: +}}|
+        {2:]] .. osjoin(fn.fnamemodify(cwd, ':~'), 'Xfile') .. [[ [RO]{MATCH: +}}|
         {MATCH: +}|
         {1:~{MATCH: +}}|
         {4:[No Name]{MATCH: +}}|
@@ -155,7 +164,7 @@ describe('vim.secure', function()
       ]])
 
       -- Trust database is not updated
-      eq(nil, read_file(stdpath('state') .. pathsep .. 'trust'))
+      eq(nil, read_file(vim.fs.joinpath(stdpath('state'), 'trust')))
 
       -- Cannot write file
       pcall_err(command, 'write')
@@ -173,7 +182,7 @@ describe('vim.secure', function()
       local cwd = fn.getcwd()
       local msg =
         'exrc: Found untrusted code. DIRECTORY trust is decided only by name, not contents:'
-      local path = ('%s%sXdir'):format(cwd, pathsep)
+      local path = osjoin(cwd, 'Xdir')
 
       -- Need to use feed_command instead of exec_lua because of the confirmation prompt
       feed_command([[lua vim.secure.read('Xdir')]])
@@ -193,11 +202,10 @@ describe('vim.secure', function()
         {MATCH: +}|
       ]])
 
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', cwd .. pathsep .. 'Xdir'), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(osjoin(cwd, 'Xdir')))
       eq(vim.NIL, exec_lua([[return vim.secure.read('Xdir')]]))
 
-      os.remove(stdpath('state') .. pathsep .. 'trust')
+      os.remove(vim.fs.joinpath(stdpath('state'), 'trust'))
 
       feed_command([[lua vim.secure.read('Xdir')]])
       screen:expect([[
@@ -218,12 +226,10 @@ describe('vim.secure', function()
 
       -- Directories aren't hashed in the trust database, instead a slug ("directory") is stored
       -- instead.
-      local expected_hash = 'directory'
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', expected_hash, cwd .. pathsep .. 'Xdir'), vim.trim(trust))
+      assert_trust_entry(('directory %s'):format(osjoin(cwd, 'Xdir')))
       eq(true, exec_lua([[return vim.secure.read('Xdir')]]))
 
-      os.remove(stdpath('state') .. pathsep .. 'trust')
+      os.remove(vim.fs.joinpath(stdpath('state'), 'trust'))
 
       feed_command([[lua vim.secure.read('Xdir')]])
       screen:expect([[
@@ -243,7 +249,7 @@ describe('vim.secure', function()
       ]])
 
       -- Trust database is not updated
-      eq(nil, read_file(stdpath('state') .. pathsep .. 'trust'))
+      eq(nil, read_file(vim.fs.joinpath(stdpath('state'), 'trust')))
 
       feed_command([[lua vim.secure.read('Xdir')]])
       screen:expect([[
@@ -259,7 +265,7 @@ describe('vim.secure', function()
       screen:expect([[
         ^{MATCH: +}|
         {1:~{MATCH: +}}|*2
-        {2:]] .. fn.fnamemodify(cwd, ':~') .. pathsep .. [[Xdir [RO]{MATCH: +}}|
+        {2:]] .. osjoin(fn.fnamemodify(cwd, ':~'), 'Xdir') .. [[ [RO]{MATCH: +}}|
         {MATCH: +}|
         {1:~{MATCH: +}}|
         {4:[No Name]{MATCH: +}}|
@@ -267,7 +273,7 @@ describe('vim.secure', function()
       ]])
 
       -- Trust database is not updated
-      eq(nil, read_file(stdpath('state') .. pathsep .. 'trust'))
+      eq(nil, read_file(vim.fs.joinpath(stdpath('state'), 'trust')))
     end)
   end)
 
@@ -281,7 +287,7 @@ describe('vim.secure', function()
     end)
 
     before_each(function()
-      n.mkdir_p(xstate .. pathsep .. (is_os('win') and 'nvim-data' or 'nvim'))
+      n.mkdir_p(vim.fs.joinpath(xstate, is_os('win') and 'nvim-data' or 'nvim'))
       t.write_file(test_file, 'test')
       t.mkdir(test_dir)
     end)
@@ -309,116 +315,101 @@ describe('vim.secure', function()
     it('trust then deny then remove a file using bufnr', function()
       local cwd = fn.getcwd()
       local hash = fn.sha256(assert(read_file(test_file)))
-      local full_path = cwd .. pathsep .. test_file
+      local full_path = osjoin(cwd, test_file)
 
       command('edit ' .. test_file)
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='allow', bufnr=0})}]]))
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', hash, full_path), vim.trim(trust))
+      assert_trust_entry(('%s %s'):format(hash, full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='deny', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', full_path), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='remove', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq('', vim.trim(trust))
+      assert_trust_entry('')
     end)
 
     it('deny then trust then remove a file using bufnr', function()
       local cwd = fn.getcwd()
       local hash = fn.sha256(assert(read_file(test_file)))
-      local full_path = cwd .. pathsep .. test_file
+      local full_path = osjoin(cwd, test_file)
 
       command('edit ' .. test_file)
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='deny', bufnr=0})}]]))
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', full_path), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='allow', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', hash, full_path), vim.trim(trust))
+      assert_trust_entry(('%s %s'):format(hash, full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='remove', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq('', vim.trim(trust))
+      assert_trust_entry('')
     end)
 
     it('trust using bufnr then deny then remove a file using path', function()
       local cwd = fn.getcwd()
       local hash = fn.sha256(assert(read_file(test_file)))
-      local full_path = cwd .. pathsep .. test_file
+      local full_path = osjoin(cwd, test_file)
 
       command('edit ' .. test_file)
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='allow', bufnr=0})}]]))
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', hash, full_path), vim.trim(trust))
+      assert_trust_entry(('%s %s'):format(hash, full_path))
 
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='deny', path=...})}]], test_file)
       )
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', full_path), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(full_path))
 
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='remove', path=...})}]], test_file)
       )
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq('', vim.trim(trust))
+      assert_trust_entry('')
     end)
 
     it('trust then deny then remove a file using path', function()
       local cwd = fn.getcwd()
       local hash = fn.sha256(assert(read_file(test_file)))
-      local full_path = cwd .. pathsep .. test_file
+      local full_path = osjoin(cwd, test_file)
 
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='allow', path=...})}]], test_file)
       )
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', hash, full_path), vim.trim(trust))
+      assert_trust_entry(('%s %s'):format(hash, full_path))
 
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='deny', path=...})}]], test_file)
       )
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', full_path), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(full_path))
 
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='remove', path=...})}]], test_file)
       )
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq('', vim.trim(trust))
+      assert_trust_entry('')
     end)
 
     it('deny then trust then remove a file using bufnr', function()
       local cwd = fn.getcwd()
       local hash = fn.sha256(assert(read_file(test_file)))
-      local full_path = cwd .. pathsep .. test_file
+      local full_path = osjoin(cwd, test_file)
 
       command('edit ' .. test_file)
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='deny', path=...})}]], test_file)
       )
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', full_path), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='allow', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('%s %s', hash, full_path), vim.trim(trust))
+      assert_trust_entry(('%s %s'):format(hash, full_path))
 
       eq(
         { true, full_path },
         exec_lua([[return {vim.secure.trust({action='remove', path=...})}]], test_file)
       )
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq('', vim.trim(trust))
+      assert_trust_entry('')
     end)
 
     it('trust returns error when buffer not associated to file', function()
@@ -431,20 +422,17 @@ describe('vim.secure', function()
 
     it('trust then deny then remove a directory using bufnr', function()
       local cwd = fn.getcwd()
-      local full_path = cwd .. pathsep .. test_dir
+      local full_path = osjoin(cwd, test_dir)
       command('edit ' .. test_dir)
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='allow', bufnr=0})}]]))
-      local trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('directory %s', full_path), vim.trim(trust))
+      assert_trust_entry(('directory %s'):format(full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='deny', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq(string.format('! %s', full_path), vim.trim(trust))
+      assert_trust_entry(('! %s'):format(full_path))
 
       eq({ true, full_path }, exec_lua([[return {vim.secure.trust({action='remove', bufnr=0})}]]))
-      trust = assert(read_file(stdpath('state') .. pathsep .. 'trust'))
-      eq('', vim.trim(trust))
+      assert_trust_entry('')
     end)
   end)
 end)
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 84eb63beea..cd6629b378 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -3040,6 +3040,160 @@ describe('LSP', function()
       }
       eq(expected, result)
     end)
+
+    it('does not crash on error response with null id (JSON-RPC 2.0 parse error)', function()
+      local result = exec_lua(function()
+        local server = assert(vim.uv.new_tcp())
+        local accepted
+        local messages = {}
+        server:bind('127.0.0.1', 0)
+        server:listen(127, function(err)
+          assert(not err, err)
+          accepted = assert(vim.uv.new_tcp())
+          server:accept(accepted)
+          accepted:read_start(require('vim.lsp.rpc').create_read_loop(function(body)
+            local payload = vim.json.decode(body)
+            if payload.method then
+              table.insert(messages, payload.method)
+              if payload.method == 'initialize' then
+                -- Send a valid initialize response first
+                local msg = vim.json.encode({
+                  id = payload.id,
+                  jsonrpc = '2.0',
+                  result = {
+                    capabilities = {},
+                  },
+                })
+                accepted:write(
+                  table.concat({ 'Content-Length: ', tostring(#msg), '\r\n\r\n', msg })
+                )
+              elseif payload.method == 'initialized' then
+                -- Then send an error response with null id (parse error per JSON-RPC 2.0 §5)
+                local msg =
+                  '{"jsonrpc":"2.0","error":{"code":-32700,"message":"Parse error"},"id":null}'
+                accepted:write(
+                  table.concat({ 'Content-Length: ', tostring(#msg), '\r\n\r\n', msg })
+                )
+              end
+            end
+          end, function()
+            if accepted and not accepted:is_closing() then
+              accepted:close()
+            end
+          end, function()
+            if accepted and not accepted:is_closing() then
+              accepted:close()
+            end
+          end))
+        end)
+        local port = server:getsockname().port
+        local on_error_called = false
+        local client_id = assert(vim.lsp.start({
+          name = 'null-id-test',
+          cmd = vim.lsp.rpc.connect('127.0.0.1', port),
+          on_error = function(_code, _err)
+            on_error_called = true
+          end,
+        }))
+        vim.lsp.get_client_by_id(client_id)
+        -- Wait for the initialized notification to be sent and the null-id error to be received
+        vim.wait(1000, function()
+          return #messages >= 2 and on_error_called
+        end)
+        if accepted and not accepted:is_closing() then
+          accepted:close()
+        end
+        server:close()
+        server:shutdown()
+        return {
+          messages = messages,
+          on_error_called = on_error_called,
+        }
+      end)
+      -- The key assertion: Neovim should not crash, and the error handler should be called
+      eq(true, result.on_error_called)
+      eq(true, #result.messages >= 2)
+    end)
+
+    it('does not misclassify server request with null id as notification', function()
+      local result = exec_lua(function()
+        local server = assert(vim.uv.new_tcp())
+        local accepted
+        local messages = {}
+        server:bind('127.0.0.1', 0)
+        server:listen(127, function(err)
+          assert(not err, err)
+          accepted = assert(vim.uv.new_tcp())
+          server:accept(accepted)
+          accepted:read_start(require('vim.lsp.rpc').create_read_loop(function(body)
+            local payload = vim.json.decode(body)
+            if payload.method then
+              table.insert(messages, payload.method)
+              if payload.method == 'initialize' then
+                local msg = vim.json.encode({
+                  id = payload.id,
+                  jsonrpc = '2.0',
+                  result = {
+                    capabilities = {},
+                  },
+                })
+                accepted:write(
+                  table.concat({ 'Content-Length: ', tostring(#msg), '\r\n\r\n', msg })
+                )
+              elseif payload.method == 'initialized' then
+                -- Send a server request with null id (invalid per JSON-RPC 2.0)
+                local msg =
+                  '{"jsonrpc":"2.0","method":"workspace/configuration","params":{"items":[]},"id":null}'
+                accepted:write(
+                  table.concat({ 'Content-Length: ', tostring(#msg), '\r\n\r\n', msg })
+                )
+              end
+            end
+          end, function()
+            if accepted and not accepted:is_closing() then
+              accepted:close()
+            end
+          end, function()
+            if accepted and not accepted:is_closing() then
+              accepted:close()
+            end
+          end))
+        end)
+        local port = server:getsockname().port
+        local on_error_called = false
+        local notification_received = false
+        local client_id = assert(vim.lsp.start({
+          name = 'null-id-request-test',
+          cmd = vim.lsp.rpc.connect('127.0.0.1', port),
+          on_error = function(_code, _err)
+            on_error_called = true
+          end,
+          handlers = {
+            ['workspace/configuration'] = function()
+              notification_received = true
+              return {}
+            end,
+          },
+        }))
+        vim.lsp.get_client_by_id(client_id)
+        vim.wait(1000, function()
+          return #messages >= 2 and (on_error_called or notification_received)
+        end)
+        if accepted and not accepted:is_closing() then
+          accepted:close()
+        end
+        server:close()
+        server:shutdown()
+        return {
+          messages = messages,
+          on_error_called = on_error_called,
+          notification_received = notification_received,
+        }
+      end)
+      -- Should be dispatched as an error, NOT silently handled as a notification
+      eq(true, result.on_error_called)
+      eq(false, result.notification_received)
+    end)
   end)
 
   describe('#dynamic vim.lsp._dynamic', function()