Fix warning when an extension is not implemented in a C plugin
Fix warning when an extension is not implemented in a C plugin

We used to erroneously display an error in that case because we asserted
the object created from the extension gtype should not be NULL.

Distrotech/libpeas,Distrotech/libpeas,gregier/libpeas,chergert/libpeas,Distrotech/libpeas,GNOME/libpeas,gregier/libpeas,gregier/libpeas,gregier/libpeas,chergert/libpeas,GNOME/libpeas,chergert/libpeas