Report details on addon crashed on initialization

If the addon is crashed on Pheix start we just log:

Required addon Ethelia is failed at Pheix::Addons::get_addons - <STDERR>
  in method get_addons at /home/kostas/git/dcms-raku/lib/Pheix/Addons.rakumod (Pheix::Addons) line 24
  in method  at /home/kostas/git/dcms-raku/lib/Pheix/App.rakumod (Pheix::App) line 16
  in block <unit> at pheix.raku line 11

Required addon Ethelia is failed at Pheix::Addons::get_addons - <STDERR>
  in method get_addons at /home/kostas/git/dcms-raku/lib/Pheix/Addons.rakumod (Pheix::Addons) line 24
  in method  at /home/kostas/git/dcms-raku/lib/Pheix/App.rakumod (Pheix::App) line 16
  in block <unit> at pheix.raku line 11

It's very unfriendly, so it's important to find a way to log actual error.