Handle adding reactions to messages from users who have blocked the bot

[TizzySaurus]

Completes the bot-side of #2486.

What

When the bot fails to add a reaction to a message because the user has the bot blocked (e.g. creating an incident, editing an eval invocation, etc.) the bot handles this via a log.debug statement, and if a message is passed to the handler then will also send a message to the message's channel in discord (which deletes after 30 seconds -- long enough to give the user a chance to unblock the bot from that message).

Works For:

• Commands
• Events
• Schedules

Testing:

To test this, simply block the bot and then either create an incident, or edit an eval command (or anything else that causes the bot to react to your message).

Example:

[wookie184]

scheduling is something that is handled by bot-core, so the fix would need to be there. The error handler should probably be ported there first, so we don't have to duplicate this in multiple places. It might make sense to have central error handling that errors from everywhere are handled by, but i've not looked into it so i'm not too sure.

[TizzySaurus]

scheduling is something that is handled by bot-core, so the fix would need to be there. The error handler should probably be ported there first, so we don't have to duplicate this in multiple places.

So are you suggesting to merge this PR as-is, and add the schedule handling to bot-core at a later time? I'd be okay with this, as long as the exceptions raised aren't going to cause sentry alerts etc.

[TizzySaurus]

For the record, @ChrisLovering and I have come up with a solution for handling errors in the schedules (see python-discord/bot-core#177).

[wookie184]

I don't understand how the bot-core PR would help. Would we have to change all uses of create_task to add an error handler? That doesn't seem great, compared to just handling it there directly.

[TizzySaurus]

I don't understand how the bot-core PR would help. Would we have to change all uses of create_task to add an error handler? That doesn't seem great, compared to just handling it there directly.

Yeah, you're right, in reality we'd want the handle_forbidden_from_block function to be in bot-core, and automatically added in create_task. I'll make that change to the bot-core PR 👍

In fact, this change would make the done_callbacks entirely pointless, since this would be in place of that. So maybe that should be removed at the same time?

[TizzySaurus]

This is essentially stalled by python-discord/bot-core#177 now. Once that's merged, I can remove handle_forbidden_from_block from here, and migrate to importing from bot-core.

[TizzySaurus]

python-discord/bot-core#177 has now been merged, so will be continuing on with this.

[TizzySaurus]

This PR is now ready for review! 🎉

[wookie184]

Tested and seems to work nicely.