GGA, GST és RMC nmea mondat értelemző refraktorálás

lib/gnss_sentences/gngst.dart

@@ -1,18 +1,37 @@
 import 'package:nmea/nmea.dart';
 
 class Gngst extends TalkerSentence {
-  static const String id = "GNGST";
+  static const String id = 'GxGST';
+
   Gngst({required super.raw});
 
   @override
-  bool get valid => super.valid && fields.length == 9;
+  bool get valid => super.valid && fields.length >= 9;
 
-  String get utcOfPositionFix => fields[1];
-  double get rms => double.parse(fields[2]);
-  double get errorEllipseSemiMajorAxis => double.parse(fields[3]);
-  double get errorEllipseSemiMinorAxis => double.parse(fields[4]);
-  double get errorEllipseOrientation => double.parse(fields[5]);
-  double get longitudeError => double.parse(fields[6]);
-  double get latitudeError => double.parse(fields[7]);
-  double get heightError => double.parse(fields[8]);
+  String get utcOfPositionFix => _field(1);
+
+  double get rms => _parseDouble(_field(2), fallback: 0.0);
+
+  double get errorEllipseSemiMajorAxis =>
+      _parseDouble(_field(3), fallback: 0.0);
+
+  double get errorEllipseSemiMinorAxis =>
+      _parseDouble(_field(4), fallback: 0.0);
+
+  double get errorEllipseOrientation => _parseDouble(_field(5), fallback: 0.0);
+
+  double get longitudeError => _parseDouble(_field(6), fallback: 0.0);
+
+  double get latitudeError => _parseDouble(_field(7), fallback: 0.0);
+
+  double get heightError => _parseDouble(_field(8), fallback: 0.0);
+
+  String _field(int index) {
+    if (index < 0 || index >= fields.length) return '';
+    return fields[index].trim();
+  }
+
+  double _parseDouble(String value, {required double fallback}) {
+    return double.tryParse(value) ?? fallback;
+  }
 }