MessageTray notification has been already deallocated

[mzur]

If I click on the notification (don't ask why) I get:

Object .Gjs_ui_messageTray_Notification (0x559e6560fc40), has been already deallocated — impossible to emit any signal on it. This might be caused by the object having been destroyed from C code using something such as destroy(), dispose(), or remove() vfuncs.

I'm willing to implement a fix but I have no clue why this error happens. Maybe the MessageTray.Source is destroyed before the MessageTray.Notification disappeared? Shouldn't it be possible to use the same source for the whole duration the extension is installed and active? As I see it, it is destroyed in some other cases, too.