Typical error handling problem in javascript

gistfile1.txt

function genericXmlParser(xml, callback){
	var parser = new xml2js.Parser();
	var isParseError = true;
	try
	{
		parser.parseString(xml, function(err,obj){
			isParseError = false;
			if(err){
				callback({error: 'XML Parsing Error'});
			}
			else{
				callback(obj);
			}
		});	
	}
	catch(e)
	{
		//for xml parsing error
		if(isParseError){
			callback({error: 'XML Parsing Error'});	
		} 
		else {
			throw e;
		}
	}
	
}