I'd say install DrKonqi if you don't have it yet, figure out how to get it to catch the crash for reporting, and then look at the backtrace to see where the crash occurs.
Qt 5.7.1 had its share of issues, but I've never seen this crash. Semicolons with spaces before them is something coders will encounter quite often, as well as anyone writing French, so any regressions in highlighting code handling this pattern should be caught and corrected quickly. (I'm still on older KF5 frameworks and applications though.)
