#43: Handle unknown/missing layer id

Example error:

[Cryptomatte][dev][ERROR] layer crypto_material (index 2) not present in metadata
...Cryptomatte/fusion/Modules/Lua/cryptomatte_utilities.lua:598: ERROR
stack traceback:
    [C]: in function 'error'
    ...Cryptomatte/fusion/Modules/Lua/cryptomatte_utilities.lua:598: in function 'log_error'
    ...iau/repo/Cryptomatte/fusion/Fuses/Matte/cryptomatte.fuse:280: in function <...iau/repo/Cryptomatte/fusion/Fuses/Matte/cryptomatte.fuse:249>
dev failed at time 971

cedricduriau / Cryptomatte

#43: Handle unknown/missing layer id #44