catch and correct possible bad values for lat/lon, add tests

lib/widgets/map/gps_controller.dart

@@ -8,9 +8,11 @@ import 'package:flutter/foundation.dart' show defaultTargetPlatform, TargetPlatf
 import '../../dev_config.dart';
 import '../../app_state.dart' show FollowMeMode;
 import '../../services/proximity_alert_service.dart';
+import '../../services/coordinate_validation.dart';
 import '../../models/osm_node.dart';
 import '../../models/node_profile.dart';
 
+
 /// Simple GPS controller that handles precise location permissions only.
 /// Key principles: 
 /// - Respect "denied forever" - stop trying
@@ -187,6 +189,21 @@ class GpsController {
 
   /// Handle incoming GPS position
   void _onPositionReceived(Position position) {
+    // Guard against malformed fixes from the platform location stack (some
+    // OEM/fused location providers occasionally emit NaN/Infinite lat/lng,
+    // especially while a fix is still being acquired). An unvalidated bad
+    // value here can crash the app at launch (via initialCenter) or corrupt
+    // the live map camera (via follow-me animateTo), so treat it like any
+    // other transient location error rather than trusting it.
+    if (!isValidCoordinate(position.latitude) || !isValidCoordinate(position.longitude)) {
+      debugPrint(
+        '[GpsController] Ignoring invalid GPS position: '
+        'lat=${position.latitude}, lng=${position.longitude}',
+      );
+      return;
+    }
+
+
     final newLocation = LatLng(position.latitude, position.longitude);
     _currentLocation = newLocation;
     
@@ -209,6 +226,7 @@ class GpsController {
   }
 
   /// Handle GPS stream errors
+
   void _onPositionError(dynamic error) {
     debugPrint('[GpsController] Position stream error: $error');
     if (_hasLocation) {

lib/widgets/map/map_position_manager.dart

@@ -3,6 +3,9 @@ import 'package:flutter_map_animations/flutter_map_animations.dart';
 import 'package:latlong2/latlong.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
+import '../../services/coordinate_validation.dart' as coord_validation;
+
+
 
 /// Manages map position persistence and initial positioning.
 /// Handles saving/loading last map position and moving to initial locations.
@@ -30,7 +33,8 @@ class MapPositionManager {
       final zoom = prefs.getDouble('last_map_zoom');
       
       if (lat != null && lng != null && 
-          _isValidCoordinate(lat) && _isValidCoordinate(lng)) {
+          coord_validation.isValidCoordinate(lat) && coord_validation.isValidCoordinate(lng)) {
+
         final validZoom = zoom != null && _isValidZoom(zoom) ? zoom : 15.0;
         _initialLocation = LatLng(lat, lng);
         _initialZoom = validZoom;
@@ -50,9 +54,10 @@ class MapPositionManager {
       try {
         final zoom = _initialZoom ?? 15.0;
         // Double-check coordinates are valid before moving
-        if (_isValidCoordinate(_initialLocation!.latitude) && 
-            _isValidCoordinate(_initialLocation!.longitude) && 
+        if (coord_validation.isValidCoordinate(_initialLocation!.latitude) &&
+            coord_validation.isValidCoordinate(_initialLocation!.longitude) &&
             _isValidZoom(zoom)) {
+
           controller.mapController.move(_initialLocation!, zoom);
           _hasMovedToInitialLocation = true;
           debugPrint('[MapPositionManager] Moved to initial location: ${_initialLocation!.latitude}, ${_initialLocation!.longitude}');
@@ -70,9 +75,10 @@ class MapPositionManager {
   Future<void> saveMapPosition(LatLng location, double zoom) async {
     try {
       // Validate coordinates and zoom before saving
-      if (!_isValidCoordinate(location.latitude) || 
-          !_isValidCoordinate(location.longitude) || 
+      if (!coord_validation.isValidCoordinate(location.latitude) ||
+          !coord_validation.isValidCoordinate(location.longitude) ||
           !_isValidZoom(zoom)) {
+
         debugPrint('[MapPositionManager] Invalid map position, not saving: lat=${location.latitude}, lng=${location.longitude}, zoom=$zoom');
         return;
       }
@@ -102,15 +108,8 @@ class MapPositionManager {
     }
   }
 
-  /// Validate that a coordinate value is valid (not NaN, not infinite, within bounds)
-  bool _isValidCoordinate(double value) {
-    return !value.isNaN && 
-           !value.isInfinite && 
-           value >= -180.0 && 
-           value <= 180.0;
-  }
-
   /// Validate that a zoom level is valid
+
   bool _isValidZoom(double zoom) {
     return !zoom.isNaN && 
            !zoom.isInfinite &&