Odd number of elements in hash assignment at lib/perl5/Mojolicious/Plugin/I18N.pm line 122.

[preaction]

It looks like the plugin does not allow a Mojo::URL object to be the first argument to url_for, though Mojolicious allows it and simply passes the URL through. It seems like the fix would be to add another check when trying to discard an element from @_:

-        shift if (@_ % 2 && !ref $_[0]) || (@_ > 1 && ref $_[-1]);
+        shift if (@_ % 2 && (!ref $_[0] || ref $_[0] eq 'Mojo::URL')) || (@_ > 1 && ref $_[-1]);