Fix integrity error handling

[jesperhodge]

Fixes openedx/modular-learning#261

Idea right now:

• Validate against duplicate values before they reach the database and cause an IntegrityError (this is not implemented here yet)
• Handle any uncaught internal errors, including integrity errors, throughout content-tagging. For security reasons we do not want to expose internal error information directly so we return a generic 500 response.
• I made a custom error handling mixin so that this is handled for the content_tagging api in general.

Question: This would be better handled at the CMS level?

Answer: There is ongoing work to fix this up, starting with a proposal. See https://openedx.slack.com/archives/CHYH0BDTR/p1775053660743269 and openedx/openedx-platform#38246 in particular.

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[kdmccormick]

@jesperhodge I agree that exception details should not be passed to the end user on a production site. However, it's useful behavior for developers. I'd expect the stack trace to be passed upwards when DEBUG==True, and a generic 500 to be shown when DEBUG==False.

Did you test with DEBUG==False? You can do django settings override, or just run the site with tutor local ....

[kdmccormick]

To you other point:

Validate against duplicate values before they reach the database and cause an IntegrityError (this is not implemented here yet)

yep, I agree. I think it's fine to either check for conflicts before renaming the tag, or use a very targeted except IntegrityError to catch the conflict.

[jesperhodge]

I did have a look at openedx/openedx-platform#38246, an ADR in review that aims to standardize errors platform-wide. (Also reviewed it and left my thoughts.)

I decided against implementing the proposed format more extensively here at this point, since there is still a lot to discuss around that.

Rather, I think it makes sense that after that ADR is finalized we just implement a top-level CMS error handler, and this temporary solution in this PR can be removed at that time.

[kdmccormick]

To close the loop on this:

Did you test with DEBUG==False? You can do django settings override, or just run the site with tutor local ....

Jesper discussed in Slack that he did test with DEBUG==False, and he and Braden confirmed that this error detail leakage is a standing issue with DRF in general.

Rather, I think it makes sense that after that ADR is finalized we just implement a top-level CMS error handler, and this temporary solution in this PR can be removed at that time.

That approach sounds good to me @jesperhodge . Could you just include a link to the ADR PR in the temporary handlers so that we remember to remove them later?

[kdmccormick]

Thanks for thinking this through and coming up with a stop-gap solution.

[kdmccormick]

Thanks for the comprehensive tests.

[kdmccormick]

Just one last request, and then we're good to merge. Thanks!