Every time I exit (window close, ALT+F4) Firefox Quantum, a few seconds later the crash reporter pops up. Nothing problematic about Firefox itself, just does this upon exiting. (Submitting the crash report always fails, too, so it's not worth bothering with.)
I just X out of the crash reporter and I haven't been worried about it, but thought I'd drop a note here.
Windows 10 Pro 1703 (work computer), 64-bit. Install path is default, and it's an upgrade. I've had Portable Firefox on my drive since I don't even know when.
FWIW, the support page is woefully out of date. References to Firefox 2... I did skim it, though.