Feat: system enrollment error - 500 error during /token

[angela-tran]

Part of #2032

• 500-level error that occurs during /token returns a JSON response that is used to send user to /enrollment/error
• /enrollment/error shows system enrollment error template
• Sentry notification is sent
• Analytic event is sent (failed access token request with status_code in event_properties)

Reviewing / testing

Similar to review steps for #2088, you can add some code locally to simulate a 500 error.
To /token, add:

        try:
+          class response:
+             def __init__(self):
+                self.status_code = 500
+
+          raise HTTPError(response=response())
           response = client.request_card_tokenization_access()
        except Exception as e:

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
benefits/enrollment
analytics.py					45
views.py					59
Project Total

This report was generated by python-coverage-comment-action

[thekaveman]

Rebased on dev to incorporate changes from #2088

[thekaveman]

This looks great. I made the suggested modification in the view and was sent to the expected error page when trying to acquire the access token.

[thekaveman]

I'm not worried about this as blocking this PR, but...

I wonder if window.location.replace is the right method here instead? Do we want to support the back button when the user is supposed to wait and not try again immediately?

[angela-tran]

I created #2119 to follow up on this