that means that that file has been damaged.
and you can only hope that this is the only file that has been damaged, because it is one of the few files that contains no data.
make a new project and copy that new project's game.rpgproject file to your existing project.
if you get another error for another file after that, then more than one file has been destroyed and you need to replace them from your last backup.
and you need to find out why the files are destroyed to prevent future repeats.
where did you store the project? (full directory path please)
was there a computer crash before this?
Kitchen counters! I am on my second version of counters. It is slow going and I always see little details that could be done better. Have to force myself to say that's good enough for now and continue on.