/usr/bin/gnome-builder:6:g_assertion_message:g_assertion_message_expr:dzl_signal_group__target_weak_notify:weak_refs_notify:g_object_unref

The Ubuntu Error Tracker has been receiving reports about a problem regarding gnome-builder. This problem was most recently seen with package version 3.30.1-6ubuntu1, the problem page at https://errors.ubuntu.com/problem/59d46e513069d99b1004b088c70d6cddc1b829bf contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.