=head2 $c->finalize_error
-Finalizes error.
+Finalizes error. If there is only one error in L</error> and it is an object that
+does C<as_psgi> or C<code> we rethrow the error and presume it caught by middleware
+up the ladder. Otherwise we return the debugging error page (in debug mode) or we
+return the default error page (production mode).
=cut