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
if ( !hasJavaScript && !hasJavaCode )
			return;
		if ( handle instanceof TableGroupHandle )
			TableGroupScriptExecutor.handleOnPrepare(
					( TableGroupHandle ) handle, executionContext );
		if ( handle instanceof ListGroupHandle )
			ListGroupScriptExecutor.handleOnPrepare(
					( ListGroupHandle ) handle, executionContext );
	}
	
	
	private void handleOnPrepare( RowHandle handle )
	{
		boolean hasJavaScript = ( handle.getOnPrepare( ) != null )
				&& ( handle.getOnPrepare( ).length( ) != 0 );
		boolean hasJavaCode = ( handle.getEventHandlerClass( ) != null )
				&& ( handle.getEventHandlerClass( ).length( ) != 0 );
		if ( !hasJavaScript && !hasJavaCode )
			return;
		RowScriptExecutor.handleOnPrepare( handle, executionContext );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.DesignVisitor#visitReportDesign(org.eclipse.birt.report.model.api.ReportDesignHandle)
	 */
	public void visitReportDesign( ReportDesignHandle handle )
	{