The String constructor for TypeError doesn't result in the message string to be printed. That's because the message is never set anywhere. Condition will give the message in getMessage(), and TypeError.getMessage() will use that if non-null, but nothing sets it. I'll attach a patch that corrects this, but I don't want to commit it yet - it looks woefully incorrect to me. Is this really what we have to do in all Condition-extending classes? Set a protected member? We already set the formatControl, why does that not work?