I found error on location.onLocationChanged() on main.dart

Does it with or without () ??

Im not able to get route between source and destination. the error is

D/BufferQueueProducer( 7109): SurfaceTexture-0-7109-0 cancelBuffer: slot 0
D/BufferQueueProducer( 7109): SurfaceTexture-0-7109-0 cancelBuffer: slot 0
V/PhoneWindow( 7109): DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@4b2d295, this = DecorView@8b3faa[MainActivity]
E/flutter ( 7109): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: The getter 'latitude' was called on null.
E/flutter ( 7109): Receiver: null
E/flutter ( 7109): Tried calling: latitude
E/flutter ( 7109): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
E/flutter ( 7109): #1 MapPageState.showPinsOnMap (package:sidebaranimationflutter/Map/map.dart:144:28)
E/flutter ( 7109): #2 MapPageState.build. (package:sidebaranimationflutter/Map/map.dart:130:17)
E/flutter ( 7109): #3 _GoogleMapState.onPlatformViewCreated (package:google_maps_flutter/src/google_map.dart:317:14)
E/flutter ( 7109): #4 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 7109): #5 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 7109): #6 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 7109): #7 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 7109): #8 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 7109): #9 Future._propagateToListeners (dart:async/future_impl.dart:709:32)
E/flutter ( 7109): #10 Future._completeWithValue (dart:async/future_impl.dart:524:5)
E/flutter ( 7109): #11 _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:32:15)
E/flutter ( 7109): #12 _completeOnAsyncReturn (dart:async-patch/async_patch.dart:290:13)
E/flutter ( 7109): #13 GoogleMapController.init (package:google_maps_flutter/src/controller.dart)
E/flutter ( 7109): #14 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 7109): #15 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 7109): #16 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 7109): #17 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 7109): #18 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 7109): #19 Future._propagateToListeners (dart:async/future_impl.dart:709:32)
E/flutter ( 7109): #20 Future._completeWithValue (dart:async/future_impl.dart:524:5)
E/flutter ( 7109): #21 _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:32:15)
E/flutter ( 7109): #22 _completeOnAsyncReturn (dart:async-patch/async_patch.dart:290:13)
E/flutter ( 7109): #23 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart)
E/flutter ( 7109): #24 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 7109): #25 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 7109): #26 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 7109): #27 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 7109): #28 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 7109): #29 Future._propagateToListeners (dart:async/future_impl.dart:709:32)
E/flutter ( 7109): #30 Future._completeWithValue (dart:async/future_impl.dart:524:5)
E/flutter ( 7109): #31 Future._asyncComplete. (dart:async/future_impl.dart:554:7)
E/flutter ( 7109): #32 _rootRun (dart:async/zone.dart:1126:13)
E/flutter ( 7109): #33 _CustomZone.run (dart:async/zone.dart:1023:19)
E/flutter ( 7109): #34 _CustomZone.runGuarded (dart:async/zone.dart:925:7)
E/flutter ( 7109): #35 _CustomZone.bindCallbackGuarded. (dart:async/zone.dart:965:23)
E/flutter ( 7109): #36 _microtaskLoop (dart:async/schedule_microtask.dart:43:21)
E/flutter ( 7109): #37 _startMicrotaskLoop (dart:async/schedule_microtask.dart:52:5)
E/flutter ( 7109):

this is Good example for live tracking but how we will stop the location updates or you can say location listener updates

I/flutter (10134): EXCEPTION CAUGHT BY IMAGE RESOURCE SERVICE 
I/flutter (10134): The following assertion was thrown resolving an image codec:
I/flutter (10134): Unable to load asset:
I/flutter (10134): 
I/flutter (10134): When the exception was thrown, this was the stack:
I/flutter (10134): #0      PlatformAssetBundle.load (package:flutter/src/services/asset_bundle.dart:221:7)
I/flutter (10134): <asynchronous suspension>
I/flutter (10134): #1      AssetBundleImageProvider._loadAsync (package:flutter/src/painting/image_provider.dart:649:31)
I/flutter (10134): #2      AssetBundleImageProvider.load (package:flutter/src/painting/image_provider.dart:630:14)
I/flutter (10134): #3      ImageProvider.resolveStreamForKey.<anonymous closure> (package:flutter/src/painting/image_provider.dart:491:13)
I/flutter (10134): #4      ImageCache.putIfAbsent (package:flutter/src/painting/image_cache.dart:359:22)
I/flutter (10134): #5      ImageProvider.resolveStreamForKey (package:flutter/src/painting/image_provider.dart:489:80)
I/flutter (10134): #6      ScrollAwareImageProvider.resolveStreamForKey (package:flutter/src/widgets/scroll_aware_image_provider.dart:106:19)
I/flutter (10134): #7      ImageProvider.resolve.<anonymous closure> (package:flutter/src/painting/image_provider.dart:330:9)
I/flutter (10134): #8      ImageProvider._createErrorHandlerAndKey.<anonymous closure>.<anonymous closure> (package:flutter/src/painting/image_provider.dart:450:26)
I/flutter (10134): (elided 13 frames from dart:async)
I/flutter (10134): 
I/flutter (10134): Image provider: AssetImage(bundle: null, name: "")
I/flutter (10134): Image key: AssetBundleImageKey(bundle: PlatformAssetBundle#13d10(), name: "", scale: 1.0)

The following assertion was thrown resolving an image codec:
Unable to load asset: 

When the exception was thrown, this was the stack: 
#0      PlatformAssetBundle.load (package:flutter/src/services/asset_bundle.dart:221:7)
<asynchronous suspension>
#1      AssetBundleImageProvider._loadAsync (package:flutter/src/painting/image_provider.dart:649:31)
#2      AssetBundleImageProvider.load (package:flutter/src/painting/image_provider.dart:630:14)
#3      ImageProvider.resolveStreamForKey.<anonymous closure> (package:flutter/src/painting/image_provider.dart:491:13)
...
Image provider: AssetImage(bundle: null, name: "")
Image key: AssetBundleImageKey(bundle: PlatformAssetBundle#13d10(), name: "", scale: 1.0)

have any idea how to fix it ?

tried to fix it by adding assets to pubspec

  assets:
    - assets/destination_map_marker.png
    - assets/driving_pin.png
    - assets/friend1.jpg
    - assets/friend2.jpg
  but didn't work

also changed a way to sync images like this:

 BitmapDescriptor.fromAssetImage(ImageConfiguration(devicePixelRatio: 2.0),
            'assets/destination_map_marker.png')
        .then((onValue) {
      destinationIcon = onValue;
    });
  }

but its not this

Tracking is working fine. But when I press the home button of the phone. Start some Other app. Then came back to the app. The map is gone/losses it's state. But the current Location Button is visible. And when I press the current location Button, The map gets it's state again. Whole screen is blank until I press the location button.

A value of type 'PolylineResult' can't be assigned to variable type 'List'.