Do not raise GICrystal::ObjectCollectedError on unsafe versions of vf…

…unc.

Soon I'll land fixes for Gtk::Expression in gtk4 shards that will depend on
this because Gtk::Expression may try to fetch object properties too early
before the Crystal instance gets instantiated.

ecr/v_func.ecr

@@ -31,7 +31,7 @@
       private def self._vfunc_unsafe_<%= vfunc.name %>(%this : Pointer(Void), <% generate_lib_args(io, vfunc) %>) : <%= return_type %>
         <%-= vfunc_gi_annotations %>
         %instance = LibGObject.g_object_get_qdata(%this, GICrystal::INSTANCE_QDATA_KEY)
-        raise GICrystal::ObjectCollectedError.new if %instance.null?
+        return <%= type_info_default_value(vfunc.return_type) %> if %instance.null?
 
         %instance.as(self).{{ impl_method_name.id }}(<% call_user_method_with_lib_args(io) %>)
       end