Error handling needed for line parsing

[adambarthelson]

port.on('data', function(line) {
        if (line == undefined || !line.match(/^\$.+\*[0-9A-F]{2}$/)) {
            return;
        }
        var data = nmea.parse(line);  // need to catch or return false if nmea.parse returns error
        if (data == undefined) {
            return;
        }
        self.emit('data',data);
        self.emit(data.type,data);
    });