itch.io

I've never seen that error before, not just for this file specifically, but in all of my time using windows. Perhaps the original file is corrupted somehow in your original location? Clearly after making the copy + paste action, the file pasted is also corrupted to throw that error.

Have you tried redownloading the plugin file and pasting that file instead? I don't think the js file has any weird file properties that would cause that error, unless some antivirus program has already been messing with it thinking that it's a malicious file or something.