Camera opens up automatically on locking/unlocking the screen in Nexus 5

[AC Question]

Hi, I am using a Nexus 5 phone with the latest version of Android. Whenever I try to lock/unlock my screen using the power button it automatically opens up the camera. I tried Force Stop the camera and restarting my phone but for no use. I think because of this issue my Torch is also not working properly. Please help.

 

[AlphaTango414]

Turn off camera quick launch.