Don't bother destroying resources after sending an error

Don't bother destroying resources after sending an error

An error makes the client exit, which cleans up the resources anyway.

Note (Jason Ekstrand):
This is safe for two reasons.  First, we should be handling object
destruction nicely anyway.  Second, in each of these cases, the resources
don't have any implementation or destruction set so it has absolutely no
effect on the rest of weston whether we destroy it now or later.