Cannot open a file

[MrSmiley006]

Hello everybody. I have a problem opening and reading a file using the "Opening a file" code from this repo. When I run the code, an exception is raised (I think it was a TypeError) that says something about indexing a nil value. Any help will be appreciated.
Edit:
The exception raised was computercraft.errors.LuaException, not TypeError.
It says: ['[string "temp["2"].close(); temp["2"] = nil:1: attempt to index field \'2\' (a nil value)']