'handler' checks in before_render hook when exception occur is not reliable

[KES777]

This is not a problem, but maybe should be taken into account: Because ->render_maybe changes stash. The M:P:DefaultHandlers:142 implicitly sets up handler to 'ep'. Thus second call to _fallbacks M:P:DefaultHelpers:123 will always try to use ..ep templates

this prevents to check format

[KES777]

format.t.txt

[KES777]

https://irclog.perlgeek.de/mojo/2018-05-23#i_16196900

[KES777]

This is because ->render_maybe changes the stash, even when operation fails.

Look at next surprising code:

package Mojolicoius:Controller:xxx;

sub yyy {
  ....
  $c->stash->{ template } =  'some/template';
  $c->render_maybe( some => 'data' ); # this deletes 'template' stash value
  $c->render;                         # here will xxx/yyy willbe rendered instead of some/template
}