Bug 140620 Chart scripting errors are ignored
Write a chart with an invalid script, the execution simply ignores the script. This makes it difficult to debug scripting. The error message is also not precise and needs improvements.
chart/org.eclipse.birt.chart.device.extension/src/org/eclipse/birt/chart/device/image/JavaxImageIOWriter.java
super.setProperty( IDeviceRenderer.GRAPHICS_CONTEXT, _img.getGraphics( ) );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.chart.device.IDeviceRenderer#after()
	 */
	public void after( ) throws ChartException
	{
		super.after( );
		if ( _oOutputIdentifier != null )
		{
			
			Iterator it = null;
			String s = getFormat( );
			if ( s != null )
			{
				it = ImageIO.getImageWritersByFormatName( s );
				if ( !it.hasNext( ) )
				{
					it = null; 
				}
			}
			
			if ( it == null )
			{
				s = getMimeType( );
				if ( s == null )
				{
					throw new ChartException( ChartDeviceExtensionPlugin.ID,