Remove a broken Flask error handler

[neob91-close]

Fixes the following error:

  File "/opt/venv/lib/python3.12/site-packages/flask/app.py", line 2213, in __call__
    return self.wsgi_app(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/venv/lib/python3.12/site-packages/flask/app.py", line 2193, in wsgi_app
    response = self.handle_exception(e)
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/venv/lib/python3.12/site-packages/flask/app.py", line 1396, in handle_exception
    handler = self._find_error_handler(server_error)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/venv/lib/python3.12/site-packages/flask/app.py", line 1242, in _find_error_handler
    handler = handler_map.get(cls)
              ^^^^^^^^^^^^^^^
AttributeError: 'function' object has no attribute 'get'

It is prudent to not return exception information in API responses anyway.