ConsistencyMessage: If no message is provided it fallbacks to constraint message

product/ERP5Type/ConsistencyMessage.py

@@ -50,6 +50,8 @@ class ConsistencyMessage(ObjectMessage):
     self.class_name = "Constraint Message"
     self.constraint_relative_url = ""
     if constraint:
+      if not message:
+        message = constraint._getMessage('message_expression_false')
       self.description = constraint.description
       self.class_name = constraint.__class__.__name__
       # keep track of the relative URL of the constraint to have it included in