X-Git-Url: http://nitlanguage.org

diff --git a/src/serialization_phase.nit b/src/serialization_phase.nit
index 7bdd2d4..73ce377 100644
--- a/src/serialization_phase.nit
+++ b/src/serialization_phase.nit
@@ -16,7 +16,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Phase generating methods to 
+# Phase generating methods to serialize Nit objects to different formats
 module serialization_phase
 
 import phase
@@ -93,6 +93,10 @@ private class SerializationPhase
 		code.add "	v.notify_of_creation self"
 
 		for attribute in npropdefs do if attribute isa AAttrPropdef then
+			if attribute.n_type == null then
+				toolcontext.error(attribute.location, "NOT YET IMPLEMENTED: all attributes of an auto_serialized class definition must define a type.")
+				continue
+			end
 			var name = attribute.name
 			var type_name = attribute.type_name
 			code.add ""