Info about compiler errors in CU

Hi all

I'm working on an improved implementation of Organize Imports, one that can
also add missing imports (so far, it only does some reformatting and removes
unused imports).

Now what I wonder is, how can I find out if a compilation unit has any compile
errors in it? I suppose I could just traverse the whole CU for TypeErrors, but
that would unnecessarily slow down all organize import actions on error-free
code..

Thanks!

Mirko