How do I shoot a random bug in Firefox Nightly?

Thank you for reporting this. You can do the following: https://support.mozilla.org/en-US/kb/firefox-crashes-asking-support https://support.mozilla.org/en-US/kb/troubleshoot-firefox-crashes-closing-or-quitting https://support.mozilla.org/en-US/kb/send-plugin-crash-reports-help-improve-firefox

If you are going to be a Nightly development channel tester then you may be interested in the builds threads in https://forums.mozillazine.org/viewforum.php?f=23 as he lists the fixes and partial fixes.