I disagree. Those are separate problems and shouldn't be combined.

Mis-closed tags are already detected and rendered harmless by the "HTML nesting enforcement" squad (enable them at Display Settings while they remain optional awaiting a couple of bug fixes). They also present the problems found to the user in hopes that they will correct them (control how much they will present to you at the same location).

Inappropriate line lengths in PRE tags likewise won't be part of "fix an unformatted node".

And the original problem here is pretty simple, despite Limbic~Region's admittedly aiming too high. I just added a reply clarifying how simple (nay, simplistic) I would like the solution to be.