I think it would be really handy if there was a Special: page that would list all pages that encountered (pre)parser errors during their last render.
My direct reasoning for these would be references. You often see that a named ref is removed that is still in use by other named refs resulting in:

Cite error: Invalid <ref> tag; no text was provided for refs named yourname

Especially on articles that are not as closely watched, these can persist for quite some time, in part because this error is at the bottom of the page and thus not that visible. We also have similar issues with parserfunctions errors, and even post expansion problems.

If we had a Special:Errors page that would list all pages that had one of those errors during their last render, then it would be much easier to solve all these issue. One of the reasons is that they often require quite some experience as an editor in order to be solved, but it can take a while before such editors either find the pages themselves, or are pointed at them. With a list, the experienced editors can regularly check wether their are issues with wikipages that have gone unnoticed and go out and fix them.

Version: unspecified
Severity: enhancement