Bug 121111 Bad event handler class name does not cause an error
Open a report design, open any Data Set's Property editor. Type in an invalid Java class name for the "Event Handler Class" property, say "aaa". Preview a report that uses that Data Set. The report executes normally. No error is shown. Event handlers are an integral part of a report design, and if a script handler class is not found, or if the handler throws a runtime exception, Report Engine should either stop the report execution, or show the error message in the generated report. (Tested with the 2005-12-15 nightly build)
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutionContext.java
{
			log.log( Level.SEVERE, e.getMessage( ), e );
			addException( new EngineException(
					MessageConstants.INVALID_EXPRESSION_ERROR, expr, e ) );
			return Boolean.FALSE;
		}
	}
	/**
	 * execute the script. simply evaluate the script, and drop the return value
	 * 
	 * @param script
	 *            script to be executed
	 */
	public void execute( String script )
	{
		if ( script != null )
		{
			evaluate( script );
		}
	}
	/**
	 * execute script. call evaluate to evaluate the script and drop the return
	 * value
	 * 
	 * @param script
	 *            script to be executed.
	 */
	public void execute( IBaseExpression script )
	{
		if ( script != null )