Null Check operator used on a null value

[Sarwer Hussain]

This error pops out on clicking Sign up Button

[InsyAravinth]

Unhandled Exception: 'package:face_net_authentication/services/camera.service.dart': Failed assertion: line 66 pos 9: '_cameraController!.value.previewSize != null': Preview size is null

How to fix the issue while sign up? (first time app opens) @hussainint @MCarlomagno