replaced scrim.registration_channel.id with scrim.registration_channel_id to prevent AttributeError when a scrim is deleted without registration channel
Checklist:
[x] I have performed a self-review of my own code.
[ ] I have commented my code, particularly in hard-to-understand areas.
Fixes #150
Description:
replaced
scrim.registration_channel.id
withscrim.registration_channel_id
to prevent AttributeError when a scrim is deleted without registration channelChecklist: