暂停扫码后，在打开扫码，报错。无法正常打开

[momtboy]

I/flutter (13541): ==============================>>>>>>>>>>>>>>null E/flutter (13541): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: The getter 'devicePixelRatio' was called on null. E/flutter (13541): Receiver: null E/flutter (13541): Tried calling: devicePixelRatio E/flutter (13541): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5) E/flutter (13541): #1 ScanViewState.startScan (package:fqreader/scan_view.dart:146:36)