Frostbite variables called end will cause a syntax error and prevent it from compiling.
In the Fog class, we have a variable called end.
If we include that variable, the script won't compile since the function will end early.
This can be solved by remapping fog.end to fog.endDistance.
fog.start should also be remapped to fog.startDistance for likeness sake.
As a workaround you can try accessing them using the brackets operator for now (ie. fog['end']).