Comment 4 for bug 194429

I stumbled onto this while searching for the same issue in my own code. This initial error (which indirectly causes the rest to occur) is the result of not initializing the GType library. Either gtk_init mush be called (when using GTK+) or g_type_init.

In this case, it sounds like somewhere in the code a GObject is being created before gtk_init is called, which should be the first thing to run. (generally it's at the very top of main)