issue with the camera attach function with the love.graphics.translate -self.x -self.y

im new to using this library and i keep getting this error that in the attach() it love.graphics.translate(-self.x,-self.y) and it says that x is a nil value. how can i fix this? pls help
Error

hump/camera.lua:119: attempt to perform arithmetic on field 'x' (a nil value)

Traceback

[love "callbacks.lua"]:228: in function 'handler'
hump/camera.lua:119: in function 'attach'
main.lua:132: in function 'draw'
[love "callbacks.lua"]:168: in function <[love "callbacks.lua"]:144>
[C]: in function 'xpcall'
heres the error.

[HDictus]

You'll need to provide a sample of code that produces the error, since this clearly doesn't happen every time someone uses camera:attach().