there's an issue at startup the program

I have a problem to run flutter_p2p test app as below.
E/flutter ( 2735): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: MissingPluginException(No implementation found for method isLocationPermissionGranted on channel de.mintware.flutter_p2p/flutter_p2p)

How can I solve it?

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1. When compile & run the this app, I can see this log

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Launching lib/main.dart on Pixel 2 in debug mode...
Running Gradle task 'assembleDebug'...
✓ Built build/app/outputs/apk/debug/app-debug.apk.
E/flutter ( 2735): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: MissingPluginException(No implementation found for method isLocationPermissionGranted on channel de.mintware.flutter_p2p/flutter_p2p)
E/flutter ( 2735): #0 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:154:7)
E/flutter ( 2735):
E/flutter ( 2735): #1 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:329:12)
E/flutter ( 2735): #2 FlutterP2p.isLocationPermissionGranted (package:flutter_p2p/plugin.dart:24:27)
E/flutter ( 2735): #3 _MyAppState._checkPermission (package:flutter_p2p_example/main.dart:149:27)
E/flutter ( 2735): #4 _MyAppState._register (package:flutter_p2p_example/main.dart:61:16)
E/flutter ( 2735): #5 _MyAppState.initState (package:flutter_p2p_example/main.dart:41:5)
E/flutter ( 2735): #6 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4640:58)
E/flutter ( 2735): #7 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4476:5)
E/flutter ( 2735): #8 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3446:14)
E/flutter ( 2735): #9 Element.updateChild (package:flutter/src/widgets/framework.dart:3214:18)
E/flutter ( 2735): #10 RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:1148:16)
E/flutter ( 2735): #11 RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:1119:5)
E/flutter ( 2735): #12 RenderObjectToWidgetAdapter.attachToRenderTree. (package:flutter/src/widgets/binding.dart:1061:17)
E/flutter ( 2735): #13 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2607:19)
E/flutter ( 2735): #14 RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:1060:13)
E/flutter ( 2735): #15 WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:941:7)
E/flutter ( 2735): #16 WidgetsBinding.scheduleAttachRootWidget. (package:flutter/src/widgets/binding.dart:922:7)
E/flutter ( 2735): #17 _rootRun (dart:async/zone.dart:1180:38)
E/flutter ( 2735): #18 _CustomZone.run (dart:async/zone.dart:1077:19)
E/flutter ( 2735): #19 _CustomZone.runGuarded (dart:async/zone.dart:979:7)
E/flutter ( 2735): #20 _CustomZone.bindCallbackGuarded. (dart:async/zone.dart:1019:23)
E/flutter ( 2735): #21 _rootRun (dart:async/zone.dart:1184:13)
E/flutter ( 2735): #22 _CustomZone.run (dart:async/zone.dart:1077:19)
E/flutter ( 2735): #23 _CustomZone.bindCallback. (dart:async/zone.dart:1003:23)
E/flutter ( 2735): #24 Timer._createTimer. (dart:async-patch/timer_patch.dart:23:15)
E/flutter ( 2735): #25 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:398:19)
E/flutter ( 2735): #26 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:429:5)
E/flutter ( 2735): #27 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
E/flutter ( 2735):
Debug service listening on ws://127.0.0.1:53833/Cv1vB8KrBmg=/ws
Syncing files to device Pixel 2...

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2. When I tab the 'Discover Devices', I can see below log

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E/flutter ( 2735): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: MissingPluginException(No implementation found for method discover on channel de.mintware.flutter_p2p/flutter_p2p)
E/flutter ( 2735): #0 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:154:7)
E/flutter ( 2735):
E/flutter ( 2735): #1 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:329:12)
E/flutter ( 2735): #2 FlutterP2p.discoverDevices (package:flutter_p2p/plugin.dart:48:27)
E/flutter ( 2735): #3 _MyAppState.build. (package:flutter_p2p_example/main.dart:192:53)
E/flutter ( 2735): #4 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:779:19)
E/flutter ( 2735): #5 _InkResponseState.build. (package:flutter/src/material/ink_well.dart:862:36)
E/flutter ( 2735): #6 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter ( 2735): #7 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:504:11)
E/flutter ( 2735): #8 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:282:5)
E/flutter ( 2735): #9 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:217:7)
E/flutter ( 2735): #10 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:475:9)
E/flutter ( 2735): #11 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:76:12)
E/flutter ( 2735): #12 PointerRouter._dispatchEventToRoutes. (package:flutter/src/gestures/pointer_router.dart:122:9)
E/flutter ( 2735): #13 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:379:8)
E/flutter ( 2735): #14 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:120:18)
E/flutter ( 2735): #15 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:106:7)
E/flutter ( 2735): #16 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:218:19)
E/flutter ( 2735): #17 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
E/flutter ( 2735): #18 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
E/flutter ( 2735): #19 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
E/flutter ( 2735): #20 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
E/flutter ( 2735): #21 _rootRunUnary (dart:async/zone.dart:1196:13)
E/flutter ( 2735): #22 _CustomZone.runUnary (dart:async/zone.dart:1085:19)
E/flutter ( 2735): #23 _CustomZone.runUnaryGuarded (dart:async/zone.dart:987:7)
E/flutter ( 2735): #24 _invoke1 (dart:ui/hooks.dart:275:10)
E/flutter ( 2735): #25 _dispatchPointerDataPacket (dart:ui/hooks.dart:184:5)
E/flutter ( 2735):

flutter verion is
➜ example dart --version
Dart VM version: 2.8.2 (stable) (Mon May 11 15:06:42 2020 +0200) on "macos_x64"
➜ example

[devtronic]

I'm already working on a fix. The problem is the method invocation by reflection. Proguard removes the methods accidentally because "they are not used".

[caustav]

Any update on the fix. Am also getting the same error.