fix: handle Forbidden when sending confirm-thread-creation DM (#3442)

[13-Prabhat]

Closes #3442

Bug

When both react to contact and confirm_thread_creation are enabled, and the recipient has DMs disabled, the confirmation prompt sent from ThreadManager.create() can raise an uncaught discord.Forbidden exception.

Because the exception occurs before view.wait() is reached, the thread remains cached in a "not ready" state and never gets cleaned up. As a result, subsequent contact attempts may report that a thread already exists, and the stale state persists until the bot is restarted.

Fix

Added a try/except discord.Forbidden block around the confirmation prompt send() call.

If the DM cannot be delivered, the code now:

• Logs a warning
• Marks the thread as cancelled
• Removes the thread from the cache
• Returns early

This mirrors the existing cleanup logic already used for the deny and timeout paths below.

Testing

• Traced the affected code path against the behavior described in the issue
• Confirmed that failed DM delivery now triggers proper cleanup
• Verified that no behavior changes occur when recipients have DMs enabled
• Ran python -m py_compile
• Applied project-standard formatting with black

The repository does not currently include an automated test suite, so validation was performed through code review and manual tracing of the execution flow.

[lorenzo132]

Hi, it looks like you are trying to merge this into the master branch.

Can you change this into the development branch?

Thanks for the PR tho!

[13-Prabhat]

Hi! I've opened a PR for this issue and implemented a fix for the thread cleanup path when DM delivery fails.

Please have a look when convenient. Feedback is welcome. Thanks!

[13-Prabhat]

Thanks for pointing that out. I've updated the PR to target the development branch now.

Please let me know if there's anything else that needs to be adjusted.

[lorenzo132]

Thanks for the PR and update.
I will check this out coming weekend

[sebkuip]

Looks good! Thanks for the PR!

Since it's a small fix, we are looking into adding it to the V4.3.0 (beta/unstable for some time) update coming soon as well. We'll update your proposed changelog entry to fit correctly into the format we'll use then.

[StephenDaDev]

I think this looks good. Thanks for your contribution!

Deployed on test instance; tested working, bug has been resolved.

Added to changelog commit e8f141

[lorenzo132]

Thanks for your contribution!

[StephenDaDev]

Thank you again for your excellent first-time contribution!