At some point we broke mojolious's built in error processing code.

Instead of a useful stack track we now get a bunch of internal Mojo error code instead and nothing useful to point at the actual underlying problem.

>>
The application raised the following error:

  Can't use an undefined value as an ARRAY reference at template mojo/debug.html.ep line 288.
Context:
  283:               </div>
  284:               <div class="tap tap-border-top">tap for more</div>
  285:             </div>
  286:           </div>
  287:           <div class="row">
  288:             % if (@{app->log->history}) {
  289:                 % my $log = join '', map { scalar app->log->format->(@$_) } @{app->log->history};
  290:                 <pre class="mojo-terminal"><code class="nohighlight"><%= $log %></code></pre>
  291:             % }
  292:             % else {
  293:               <div class="alert alert-warning wide" role="alert">
Traceback (most recent call first):
  File "template mojo/debug.html.ep", line 288, in "Mojo::Template::Sandbox::6bff7bf20514502e6c04c41933771297"

. . . internal mojo stuff

  File "/usr/bin/starman", line 38, in "main"

and the StackTrace middleware couldn't catch its stack trace, possibly because your application overrides $SIG{__DIE__} by itself, preventing the middleware from working correctly. Remove the offending code or module that does it: known examples are CGI::Carp and Carp::Always.

For example

I traced this back a little in the server logs where it points to Koha::Logger not implimenting the 'history' method.