fix no tile return value

packages/google_maps_flutter/google_maps_flutter/example/integration_test/google_maps_test.dart

@@ -1131,60 +1131,60 @@ void main() {
     },
   );
 
-  // testWidgets(
-  //   'remove tileOverlays correctly',
-  //   (WidgetTester tester) async {
-  //     Completer<GoogleMapInspector> inspectorCompleter =
-  //         Completer<GoogleMapInspector>();
-  //     final Key key = GlobalKey();
-  //     final TileOverlay tileOverlay1 = TileOverlay(
-  //       tileOverlayId: TileOverlayId('tile_overlay_1'),
-  //       tileProvider: _DebugTileProvider(),
-  //       zIndex: 2,
-  //       visible: true,
-  //       transparency: 0.2,
-  //       fadeIn: true,
-  //     );
-
-  //     await tester.pumpWidget(
-  //       Directionality(
-  //         textDirection: TextDirection.ltr,
-  //         child: GoogleMap(
-  //           key: key,
-  //           initialCameraPosition: _kInitialCameraPosition,
-  //           tileOverlays: <TileOverlay>{tileOverlay1},
-  //           onMapCreated: (GoogleMapController controller) {
-  //             final GoogleMapInspector inspector =
-  //                 // ignore: invalid_use_of_visible_for_testing_member
-  //                 GoogleMapInspector(controller.channel);
-  //             inspectorCompleter.complete(inspector);
-  //           },
-  //         ),
-  //       ),
-  //     );
-
-  //     final GoogleMapInspector inspector = await inspectorCompleter.future;
-
-  //     await tester.pumpWidget(
-  //       Directionality(
-  //         textDirection: TextDirection.ltr,
-  //         child: GoogleMap(
-  //           key: key,
-  //           initialCameraPosition: _kInitialCameraPosition,
-  //           onMapCreated: (GoogleMapController controller) {
-  //             fail('OnMapCreated should get called only once.');
-  //           },
-  //         ),
-  //       ),
-  //     );
-
-  //     await tester.pumpAndSettle(const Duration(seconds: 3));
-  //     Map<String, dynamic> tileOverlayInfo1 =
-  //         await inspector.getTileOverlayInfo('tile_overlay_1');
-
-  //     expect(tileOverlayInfo1, isNull);
-  //   },
-  // );
+  testWidgets(
+    'remove tileOverlays correctly',
+    (WidgetTester tester) async {
+      Completer<GoogleMapInspector> inspectorCompleter =
+          Completer<GoogleMapInspector>();
+      final Key key = GlobalKey();
+      final TileOverlay tileOverlay1 = TileOverlay(
+        tileOverlayId: TileOverlayId('tile_overlay_1'),
+        tileProvider: _DebugTileProvider(),
+        zIndex: 2,
+        visible: true,
+        transparency: 0.2,
+        fadeIn: true,
+      );
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: GoogleMap(
+            key: key,
+            initialCameraPosition: _kInitialCameraPosition,
+            tileOverlays: <TileOverlay>{tileOverlay1},
+            onMapCreated: (GoogleMapController controller) {
+              final GoogleMapInspector inspector =
+                  // ignore: invalid_use_of_visible_for_testing_member
+                  GoogleMapInspector(controller.channel);
+              inspectorCompleter.complete(inspector);
+            },
+          ),
+        ),
+      );
+
+      final GoogleMapInspector inspector = await inspectorCompleter.future;
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: GoogleMap(
+            key: key,
+            initialCameraPosition: _kInitialCameraPosition,
+            onMapCreated: (GoogleMapController controller) {
+              fail('OnMapCreated should get called only once.');
+            },
+          ),
+        ),
+      );
+
+      await tester.pumpAndSettle(const Duration(seconds: 3));
+      Map<String, dynamic> tileOverlayInfo1 =
+          await inspector.getTileOverlayInfo('tile_overlay_1');
+
+      expect(tileOverlayInfo1, isNull);
+    },
+  );
 }
 
 class _DebugTileProvider implements TileProvider {

packages/google_maps_flutter/google_maps_flutter/example/lib/tile_overlay.dart

@@ -87,15 +87,15 @@ class TileOverlayBodyState extends State<TileOverlayBody> {
             ),
           ),
         ),
-        FlatButton(
+        TextButton(
           child: const Text('Add tile overlay'),
           onPressed: _addTileOverlay,
         ),
-        FlatButton(
+        TextButton(
           child: const Text('Remove tile overlay'),
           onPressed: _removeTileOverlay,
         ),
-        FlatButton(
+        TextButton(
           child: const Text('Clear tile cache'),
           onPressed: _clearTileCache,
         ),

packages/google_maps_flutter/google_maps_flutter/ios/Classes/FLTGoogleMapTileOverlayController.m

@@ -131,7 +131,11 @@ - (void)requestTileForX:(NSUInteger)x
               UIImage* tileImage;
               if ([result isKindOfClass:[NSDictionary class]]) {
                 FlutterStandardTypedData* typedData = (FlutterStandardTypedData*)result[@"data"];
-                tileImage = [UIImage imageWithData:typedData.data];
+                if (typedData == nil) {
+                  tileImage = kGMSTileLayerNoTile;
+                } else {
+                  tileImage = [UIImage imageWithData:typedData.data];
+                }
               } else {
                 if ([result isKindOfClass:[FlutterError class]]) {
                   FlutterError* error = (FlutterError*)result;

packages/google_maps_flutter/google_maps_flutter/lib/src/google_map.dart

@@ -396,15 +396,15 @@ class _GoogleMapState extends State<GoogleMap> {
 
   // Returns the [Tile] from an added [TileOverlay].
   //
-  // If the TileOverlay or his TileProvider is not found,
+  // If the TileOverlay or its TileProvider is not found,
   // a [TileProvider.noTile] is returned.
   Future<Tile> _onGetTile(
       String tileOverlayIdRaw, int x, int y, int zoom) async {
     assert(tileOverlayIdRaw != null);
     final TileOverlayId tileOverlayId = TileOverlayId(tileOverlayIdRaw);
     final TileOverlay tileOverlay = _tileOverlays[tileOverlayId];
     if (tileOverlay == null || tileOverlay.tileProvider == null) {
-      return null;
+      return TileProvider.noTile;
     }
     return await tileOverlay.tileProvider.getTile(x, y, zoom);
   }