Print exception if marshalling a signal argument fails
Print exception if marshalling a signal argument fails

For example if cairo support is missing a Gtk.Widget::draw call
will result in
"TypeError: Couldn't find foreign struct converter for 'cairo.Context'"

https://bugzilla.gnome.org/show_bug.cgi?id=748198

pexip/pygobject,GNOME/pygobject,pexip/pygobject,GNOME/pygobject,pexip/pygobject,GNOME/pygobject