GstPlayer: accessing pipeline from GJS causes ref count error on exit

I am trying to use GstPlayer in GJS via GI bindings. Everything initially works, but when I access the player pipeline (playbin) either via get_pipeline method or simply by pipeline property. I get following error on app exit:

gst_object_unref: assertion '((GObject *) object)->ref_count > 0' failed

This is probably caused by GJS automatically decreasing pipeline reference count when done with it. After playback, when main loop finishes the gstplayer also tries to decrease the count thus reaching minus value.

The error is generated by this line in gstplayer.c.