Invalid webhook list name causes exception

[brotskydotcom]

Found these lines in the running server log:

Jul 29 12:31:11 bdc-public-services app/web.1 Processing webhook items on 'None'...
Jul 29 12:31:11 bdc-public-services app/web.1 Task exception was never retrieved
Jul 29 12:31:11 bdc-public-services app/web.1 future: <Task finished name='Task-393' coro=<transfer_all_webhook_items() done, defined at /app/app/workers/webhook_transfer.py:114> exception=AttributeError("'NoneType' object has no attribute 'split'")>
Jul 29 12:31:11 bdc-public-services app/web.1 Traceback (most recent call last):
Jul 29 12:31:11 bdc-public-services app/web.1   File "/app/app/workers/webhook_transfer.py", line 121, in transfer_all_webhook_items
Jul 29 12:31:11 bdc-public-services app/web.1     retry_list = await process_items(try_list)
Jul 29 12:31:11 bdc-public-services app/web.1   File "/app/app/workers/webhook_transfer.py", line 45, in process_items
Jul 29 12:31:11 bdc-public-services app/web.1     environ, guid, retry_count = list_key.split(":")
Jul 29 12:31:11 bdc-public-services app/web.1 AttributeError: 'NoneType' object has no attribute 'split'

Clearly the fact that None was used as a key in a processing list is also a bug. But we shouldn't crash because of it. That's this bug.

[brotskydotcom]

This is actually a symptom of #22. Closing this one as a dup.