Youtube_player_flutter: O método deactivate() dá erro

Quando eu navego na página contém player de vídeo para outra página, dá erro em _controller.pause(); linha.

void desativar() {
_controller.pause();
super.desativar();
}

Log de eventos abaixo:

W/ScreenOrientationListener(17293): Removendo um observador inexistente!
C/cromo(17293): [AVISO:aw_contents.cc(315)] SP>>> Destruir
I/cromo(17293): [INFO:synchronous_compositor_impl.cc(111)] [SynchronousCompositorImpl::SetClient] [0x0000007f359b5ec0]
I/MediaCodec(17293): [release]line:383 [OMX.google.opus.decoder]+++
I/ACodec (17293): freeBuffersOnPort portIndex 0
I/ACodec (17293): freeBuffersOnPort portIndex 1
I/MediaCodec(17293): [onMessageReceived]line:1268 [OMX.google.opus.decoder][what=kWhatShutdownCompleted][state 10][msg='AMessage(what = 'codc', target = 2) = {
I/MediaCodec(17293): int32_t what = 1935896429
I/MediaCodec(17293): }' ]
I/MediaCodec(17293): [~MediaCodec]linha:205 [][mState 0]+++
I/MediaCodec(17293): [versão] linha: 383 [OMX.MTK.VIDEO.DECODER.VP9]+++
I/ACodec (17293): freeBuffersOnPort portIndex 0
I/ACodec (17293): freeBuffersOnPort portIndex 1
I/MediaCodec(17293): [onMessageReceived]line:1268 [OMX.MTK.VIDEO.DECODER.VP9][what=kWhatShutdownCompleted][state 10][msg='AMessage(what = 'codc', target = 5) = {
I/MediaCodec(17293): int32_t what = 1935896429
I/MediaCodec(17293): }' ]
I/MediaCodec(17293): [~MediaCodec]linha:205 [][mState 0]+++
E/flutter (17293): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Exceção não tratada: MissingPluginException(Nenhuma implementação encontrada para o método assessmentJavascript no canal plugins.flutter.io/webview_0)
E/flutter (17293): #0 MethodChannel.invokeMethod (pacote: flutter/src/services/platform_channel.dart:314:7)
E/flutuação (17293):
E/flutter (17293): #1 MethodChannelWebViewPlatform.evaluateJavascript (pacote:webview_flutter/src/webview_method_channel.dart:90:21)
E/flutter (17293): #2 WebViewController.evaluateJavascript (pacote:webview_flutter/webview_flutter.dart:626:39)
E/flutter (17293): #3 YoutubePlayerController._callMethod (pacote:youtube_player_flutter/src/utils/youtube_player_controller.dart:180:32)
E/flutter (17293): #4 YoutubePlayerController.pause (pacote:youtube_player_flutter/src/utils/youtube_player_controller.dart:194:19)
E/flutter (17293): #5 _VideosScreenState.deactivate (pacote:youvilist/videosScreen.dart:133:34)
E/flutter (17293): #6 StatefulElement.deactivate (pacote: flutter/src/widgets/framework.dart:4135:12)
E/flutter (17293): #7 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1756:13)
E/flutter (17293): #8 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #9 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #10 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #11 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #12 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #13 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #14 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #15 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #16 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #17 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #18 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #19 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #20 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #21 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #22 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #23 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #24 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #25 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #26 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #27 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #28 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #29 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #30 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #31 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #32 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #33 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #34 ComponentElement.visitChildren (pacote: flutter/src/widgets/framework.dart:3990:14)
E/flutter (17293): #35 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #36 SingleChildRenderObjectElement.visitChildren (pacote: flutter/src/widgets/framework.dart:5115:14)
E/flutter (17293): #37 _InactiveElements._deactivateRecursively (pacote: flutter/src/widgets/framework.dart:1758:13)
E/flutter (17293): #38
Com cromo(17293): [AVISO:aw_network_delegate.cc(86)] https://r1---sn-nx5cvox-5uie.googlevideo.com/videoplayback?expire=1574443433&ei=ScXXXdWBL-TyxgKpl6m4Cw&ip=193.140.87.3&id= o-AF9ENbMJOc9OV4_Vekvta7EBAEi0vBUovMb0P1U1ZsBL & itag = 248 & aitags = 133% 2C134% 2C135% 2C136% 2C137% 2C160% 2C242% 2C243% 2C244% 2C247% 2C248% 2C278 & fonte = youtube & requireSSL = sim & mm = 31% 2C29 & MN = sn-nx5cvox-5uie% 2Csn-nv47lnsy & ms = au% 2Crdu & mv = m & MVI = 0 & pl = 22 & initcwndbps = 652500 & mime = vídeo% 2Fwebm & gir = sim & clembuterol = 167339651 & dur = 1537,920 & lmt = 1570277496757063 & mt = 1574421761 & fvip = 1 & keepalive = sim & fexp = 23842630 & C = WEB_EMBEDDED_PLAYER & TXP = 5535432 & sparams = expirar% 2Cei% 2Cip% 2Cid% 2Caitags% 2Csource% 2Crequiressl% 2Cmime % 2Cgir% 2Cclen% 2Cdur% 2Clmt & sig = ALgxI2wwRgIhAOsRGl_ihaPDxnSFt_2PeeuiQ9wAOw7qpXSrZLniIAn2AiEAgvZLPGOc2uPcqQtKuCuknRk6spcWaQ1Ops0Ff7ucV-Y% 3D & lsparams = milímetros% 2Cmn% 2cms% 2Cmv% 2Cmvi% 2Cpl% 2Cinitcwndbps & LSIG = AHylml4wRQIgVci2Rv - Q2ngHQ_cosnpEL1lYD13oiqr71DdTHXOYMACIQDYW1uinNm8Mk6Esy8uLh2UObVCy7Eiw8HQGHgbhrtBNg% 3D% 3D & alr = sim & cpn = PjP8wnSh2Ki85Zot & cver = 20191 121&range=4746501-6314657&rn=9&rbuf=27201#-3#1
E/cromo(17293): [ERRO:deferred_gpu_command_service.cc(76)] Nenhum renderizador de hardware. Impasse provável