ofono plugin not loading

Running gnome-calls -p ofono leads to an error:

(sm.puri.Calls:873974): libpeas-CRITICAL **: 14:17:15.285: peas_object_module_register_extension_type: assertion 'g_type_is_a (impl_type, exten_type)' failed

!277 (merged) found this issue. It's not immediately obvious to me, why this should fail