Thanks for sending it.
No, you are not the first, but for some reason this error does not appear for many people. In my discord only one person confirmed the error.
I can't figure out where it's coming from, because the variable that is specified is present in the code. I don't find any errors in the code.
The only guess I have is that you used the save from the very first chapter. There were significant changes in the code later. If you do not mind, write back, it was a new game, or loading an old save?