Why track these in Google Analytics?
The less errors a form generates = the more form completions & conversions the site will generate.
Granted, there will be many sessions where users generate field errors, but persevere nonetheless and complete the form. However, we’ve found that after analysing 1000s of forms, across millions of sessions, the lower the error rate in the session, the more conversions.
If Google Analytics isn’t tracking these, then you’ll be analysing and optimising these forms blind.