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/api/impl/ScriptedDesignVisitor.java
* the execution context to execute the onPrepare script
	 */
	protected ExecutionContext executionContext;
	/**
	 * constructor
	 * 
	 * @param handle -
	 *            the entry point to the DE report design IR
	 * @param executionContext -
	 *            the execution context to execute the onPrepare script
	 */
	ScriptedDesignVisitor( ReportDesignHandle handle,
			ExecutionContext executionContext )
	{
		super( );
		this.handle = handle;
		this.executionContext = executionContext;
	}
	private void handleOnPrepare( ReportItemHandle handle )
	{
		boolean hasJavaScript = ( handle.getOnPrepare( ) != null )
				&& ( handle.getOnPrepare( ).length( ) != 0 );
		boolean hasJavaCode = ( handle.getEventHandlerClass( ) != null )
				&& ( handle.getEventHandlerClass( ).length( ) != 0 );
		if ( !hasJavaScript && !hasJavaCode )
			return;
		if ( handle instanceof DataItemHandle )
		{
			DataItemScriptExecutor.handleOnPrepare( ( DataItemHandle ) handle,
					executionContext );