Respect locale in FailureApp when handling an unconfirmed user

[codener]

Hello there. I was debugging an issue and found this #5567. I believe this is related, and I found #5247 (comment) as well.

Background: We have recently turned our codebase from a two-locale application to a single-locale application. Further, the default locale is still :de, while the application is only available in :en. I know that should be aligned, but please bear with me – be believe this constellation exposes the issue.

My observation:

1. I am trying to sign in in :en.
2. Something "invisible" kills my request and redirects to the sign-in page – but in :de. That's wrong. There's nothing in the logs, the request does not even arrive in my controller action.
3. I believe my request was killed by lib/devise/hooks/activatable.rb. I'm not sure how it got triggered, because my session#create action has not even been called. It must be some before action hook, but the app is complex.
4. Its throw :warden ... gets caught by a Devise middleware, which invokes the FailureApp. When poking around there, a :locale is missing (as normally set in https://github.com/heartcombo/devise/pull/5567/files#diff-829736526e62456111dc08149318d7528bb478fabbda74ee6620e358833d8674R48).

I could patch this by overriding #i18n_locale in my already present custom failure app, but I believe this is an issue related to #5567 and should be fixed in Devise.

wdyt?

[carlosantoniodasilva]

Thanks for your report, I think it makes sense... it's definitely possible I have missed passing the locale around in a place or two that throw :warden, so I'll have to revisit that and maybe try adding a failing test to catch the issue.

[carlosantoniodasilva]

Update: I have a potential fix for it in #5815, passing the locale around with throw :warden calls.

[codener]

Thank you!
And have a happy new year!