ChangeJson: Catch RuntimeException in fallback check handlers

There are almost certainly more bugs like I439dfc2cd lurking, where a
missing database entity results in a NullPointerException, and falling
back to the check-only path would be more useful than letting the
error propagate.

Change-Id: If8b6e969fcebf2388753c9cc2e1eed1533a6cbbc
1 file changed