Custom error handling for: attempt to index global 'grpc' (a nil value)

[rkusa]

The most common error I see support requests for is:

attempt to index global 'grpc' (a nil value)

I'd thus suggest that we add a manual check for whether grpc is defined and if not, stop everything else from running and print out a more helpful error message. Something in the lines of check your MissionScripting.lua.