With this change, the error handling and request logging are all done in defers
after calling inner.ServeHTTP. This ensures that any recovered values which we
want to re-panic with retain a useful stacktrace. However, we now only
re-panic from errorHandler when there's no outside logHandler. Which if you're
using StdHandler there always is. We prefer this to ensure that we are able to
write a 500 Internal Server Error to the client. If a panic hits http.Server
then the response is not sent back.
Updates #12784
Signed-off-by: Paul Scott <paul@tailscale.com>
d97cddd876