Today, TL is used helpfully on code dump questions on SO, but the new OT reasons are where this is now correctly addressed. SO can use "Large blocks of code with requests for debugging without meaningful supporting info" as a specific OT reason.
But there is no such Off-Topic reason (maybe it has changed since?), so the next best candidate is:
This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting.
Is this the reason I should use when closing any and all "what's wrong with my code" + code-dump questions?