Nobody ever runs `make check-includes` with fuzzing enabled. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-None: `handle_peer_error_or_warning()` in `common/read_peer_message.{c, h}` is responsible for parsing any incoming `error` or `warning` messages as defined in BOLT #1. Add a test for it.