Are you sure the message was not that a tab had crashed? Gah-Your-tab-just-crashed https://support.mozilla.org/en-US/kb/troubleshoot-firefox-crashes-closing-or-quitting

Not a tab crash, but the Firefox browser itself. The message in the box says 'sorry your Firefox browser crashed...', even though it is still running with all the tabs viable. I just delete the message box and go on with my browsing.

Did you check about:crashes ?

I didn't check about crashes, because the browser isn't crashing. Just an error box shows up claiming that the browser crashed when in fact it did not. It's not a big deal, just an annoyance that I wondered if anyone else had a solution to.

Please check anyway.

I checked and saw that all the articles are about Firefox crashing or hanging, non of which applies to my issue.