What's with "Invalid Embed directive in stylesheet - can't resolve source" compile errors

Hi

Quite often I notice that I get lots compile errors like "Invalid Embed directive in stylesheet - can't resolve source 'Embed("assets/icons/cancelOnWhite_12x12.png")'.line 165application.css"

ONLY when there are other compile errors. As soon as I fix these other errors, all "Invalid Embed directive" errors disappear.

Obviously these errors should never show in the first place, and I wonder if this is a known problem with an existing bug report?