in inspector not recognising script properly onley on camera?

in my camera script is ok but when ever start my project on camera script gives nullrnullreferenceexception.
but am shore about my script there is no bug
what happens is in inspector if I remove the camera script and one more time drage and drop the same script it runs properly .
if I turn off and on same project it gives same problem .then want to remove camera script and drag and drop it in inspector it’s work properly
what’s the problem?
it gives only on camera remaining work properly.

[110368-thirdepersoncamera.txt|110368]