Attaching gdb and running with G_DEBUG=fatal-warnings is not a very
fast to debug a specific issue (especially if you have warnings at
startup, since then you need to run the shell from a terminal).
Instead, introduce a new SHELL_DEBUG environment variable that can
be set to backtrace-warning, causing a gjs_dumpstack() after every
warning or critical.
https://bugzilla.gnome.org/show_bug.cgi?id=700262
12ba2b222f