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.engine/src/org/eclipse/birt/chart/script/ScriptHandler.java
* Finds the JavaScript funtion by given name.
	 * 
	 * @param sFunctionName
	 *            The name of the function to be searched for
	 * @return An instance of the function being searched for or null if it
	 *         isn't found
	 */
	private final Function getJavascriptFunction( String sFunctionName )
	{
		
		
		if ( javaScriptFunctionNamesCache == null
				|| javaScriptFunctionNamesCache.indexOf( sFunctionName ) < 0 )
		{
			return null;
		}
		Context.enter( );
		try
		{
			final Object oFunction = scope.get( sFunctionName, scope );
			if ( oFunction != Scriptable.NOT_FOUND
					&& oFunction instanceof Function )
			{
				return (Function) oFunction;
			}
			return null;
		}
		finally
		{
			Context.exit( );