Not working on Null Safety | Useless

[HKTareen]

Error: MissingPluginException(No implementation found for method scanQR on
channel com.aeologic.adhoc.qr_utils)
at Object.throw_ [as throw] (http://localhost:51398/dart_sdk.js:5405:11)
at MethodChannel._invokeMethod
(http://localhost:51398/packages/flutter/src/services/restoration.dart.lib.j
s:1618:21)
at _invokeMethod.next ()
at http://localhost:51398/dart_sdk.js:43063:33
at _RootZone.runUnary (http://localhost:51398/dart_sdk.js:42919:58)
at _FutureListener.thenAwait.handleValue
(http://localhost:51398/dart_sdk.js:37493:29)
at handleValueCallback (http://localhost:51398/dart_sdk.js:38088:49)
at Function._propagateToListeners
(http://localhost:51398/dart_sdk.js:38126:17)
at _Future.new.[_completeWithValue]
(http://localhost:51398/dart_sdk.js:37955:23)
at async._AsyncCallbackEntry.new.callback
(http://localhost:51398/dart_sdk.js:37991:35)
at Object._microtaskLoop (http://localhost:51398/dart_sdk.js:43223:13)
at _startMicrotaskLoop (http://localhost:51398/dart_sdk.js:43229:13)
at http://localhost:51398/dart_sdk.js:38359:9