Bug 141255 No error for the incompatible parameter value
Steps to reproduce: 1.New a decimal parameter, set the default value to "aaa" 2.Preview the report by "Preview" tab Expected result: Error to say the incompatible parameter value Actual result: Parameter request page keeps poping up till input the decimal value Note: if preview in Web Viewer, error will be thrown out, but no exception description.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/context/ViewerAttributeBean.java
/**
	 * Init the bean.
	 * 
	 * @param request
	 * @throws Exception
	 */
	protected void __init( HttpServletRequest request ) throws Exception
	{
		if ( ParameterAccessor.isGetImageOperator( request ) )
		{
			return;
		}
		this.category = "BIRT"; 
		this.masterPageContent = ParameterAccessor
				.isMasterPageContent( request );
		this.isDesigner = ParameterAccessor.isDesigner( request );
		this.bookmark = ParameterAccessor.getBookmark( request );
		this.reportPage = String.valueOf( ParameterAccessor.getPage( request ) );
		this.reportDocumentName = ParameterAccessor.getReportDocument( request );
		this.reportDesignName = ParameterAccessor.getReport( request );
		this.format = ParameterAccessor.getFormat( request );
		this.maxRows = ParameterAccessor.getMaxRows( request );
		
		ReportEngineService.getInstance( ).setMaxRows( this.maxRows );
		
		processReport( request );
		
		String title = null;
		if ( title == null || title.trim( ).length( ) <= 0 )
		{