ipn/ipnlocal: discard cached netmaps upon panic during SetNetworkMap (#19414)

For debugging purposes, unstable builds will sometimes intentionally panic for
unexpected behaviours. We observed such a panic after loading a cached netmap,
but because we had a valid cached map, the client was unable to recover on its
own and the operator had to manually reset the cache.

As a defensive hedge, when netmap caching is enabled, check for a panic during
installation of a net network map: If one occurs, discard any cached netmaps
before letting the panic unwind, so that we do not lose the panic itself, but
reduce the need for manual intervention.

Updates #12639
Updates tailscale/corp#27300

Change-Id: I0436889c6bdc2fa728c9cb83630cd7b00a72ce68
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>

0 files changed, 0 insertions, 0 deletions