attempt to index local 'layer' (a nil value)

[MexaFoxesStudios]

Error
This sti worked very well until I added attach and detach to the code, to be able to declare the layers for a tiled map

libreries/sti/init.lua:926: attempt to index local 'layer' (a nil value)

Traceback

[love "callbacks.lua"]:228: in function 'handler'
libreries/sti/init.lua:926: in function 'drawLayer'
main.lua:75: in function 'draw'
[love "callbacks.lua"]:168: in function <[love "callbacks.lua"]:144>
[C]: in function 'xpcall'

[nirokay]

do you have a code example?