Description of problem:
The exception was quite unclear at the beginning as it said "Could not find exception handler for org.drools.WorkItemHandlerNotFoundException while executing node 3". From the System.err I found out that "Could not find work item handler for Send Task" was the root. The trick is there was no human task nor anything else that would require work item handler. However as I found out later there is a static code in message end event that executes work item.
I expected sending the messages to work the similar way as receiving them - via ksession.signalEvent().
Furthermore the workItem created always has name "Send Task" which causes confusion as I would expect it to have messageRef as a name.

Version-Release number of selected component (if applicable):
BRMS-5.3.0-ER4

How reproducible:
Every time

Steps to Reproduce:
1. start 'BPMN2-MessageEndEvent.bpmn2' process without setting the WorkItem handler
  
Actual results:
java.lang.IllegalArgumentException: Could not find exception handler for org.drools.WorkItemHandlerNotFoundException while executing node 3

Expected results:
More clear exception, ideally none

Additional info: static code in EndNode action generated from EndEventHandler (lines 152-157)

org.drools.process.instance.impl.WorkItemImpl workItem = new org.drools.process.instance.impl.WorkItemImpl();
workItem.setName("Send Task");
workItem.setParameter("MessageType", "java.lang.Object");
((org.drools.process.instance.WorkItemManager) kcontext.getKnowledgeRuntime().getWorkItemManager()).internalExecuteWorkItem(workItem);