Uncaught exception on login

[hmpf]

In the UI, when logging in on a testing branch where I had not added some config the branch expected to be there, I got a popup with:

"500 Internal Server Error: The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application."

When I try to click on the expand button I get a new error, which has a working expand-button:

Traceback (most recent call last):
  File "/../.virtualenvs/howitz/lib/python3.10/site-packages/flask/app.py", line 1484, in full_dispatch_request
    rv = self.dispatch_request()
  File "/../.virtualenvs/howitz/lib/python3.10/site-packages/flask/app.py", line 1469, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "/HOME/../howitz/src/howitz/endpoints.py", line 778, in show_maximized_error_alert
    err_description = session["errors"][alert_id]
  File "/../.virtualenvs/howitz/lib/python3.10/site-packages/flask/sessions.py", line 79, in __getitem__
    return super().__getitem__(key)
KeyError: 'errors'

If I click away this error and attempt to expand the first error again I get:

Traceback (most recent call last):
  File "/../.virtualenvs/howitz/lib/python3.10/site-packages/flask/app.py", line 1484, in full_dispatch_request
    rv = self.dispatch_request()
  File "/../.virtualenvs/howitz/lib/python3.10/site-packages/flask/app.py", line 1469, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "/HOME/../howitz/src/howitz/endpoints.py", line 778, in show_maximized_error_alert
    err_description = session["errors"][alert_id]
KeyError: 'd5ce616f-9e97-4fa6-be32-a20c31495bbf'