fixes bug in routine yac_instance_add_field

src/instance.c

@@ -1404,11 +1404,7 @@ struct coupling_field * yac_instance_add_field(
     YAC_ASSERT_F(
       strcmp(yac_get_coupling_field_name(cpl_field), field_name) ||
       (yac_get_coupling_field_component(cpl_field) != component) ||
-      (yac_coupling_field_get_basic_grid(cpl_field) != grid) ||
-      (yac_coupling_field_get_num_interp_fields(cpl_field) != num_interp_fields) ||
-      memcmp(
-        (void*)yac_coupling_field_get_interp_fields(cpl_field),
-        (void*)interp_fields, num_interp_fields * sizeof(*interp_fields)),
+      (yac_coupling_field_get_basic_grid(cpl_field) != grid),
       "ERROR(yac_instance_add_field): "
       "field with the name \"%s\" has already been defined",
       field_name);