There is a very old bug where IABot occasionally leaves an empty argument "|4=" (the "4" could be any number from 1-9) in citation templates.

If the cause of the bug can't be easily fixed, it might be easy to scan for and remove before saving the page. This would be more efficient than saving the page with the bug, then my bot checks for and removes later.

Testcases page for debugging:

https://en.wikipedia.org/wiki/User:GreenC/testcases/doublepipebug