I have a Nexus 5 running android 6.0.1 and I'm using the google camera 3.2.045. After taking a picture and locking the phone just after, when i open my phone again i got a system message saying "can't access to camera" with 2 possibile options: ignore and report. So i closed the app, but every time I open it up again or I try to take a picture also with others app but i get the same message. What should I do?