Currently a FlowableException is indeed thrown when the option is selected and there are no hits when executing the decision table.
Looking at it now I see that it would make sense to either;
provide the options to specify if a BPMN Error (and with what code) or a Java exception should be thrown when there are no hits.
or to provide the same exception mapping mechanisme that is available on service tasks
Could you raise a GitHub issue for this if you would like to see this implemented?