It seems to be something with the Il-103 package, a character not decoded. I’m downloading it to discover what is happening. You can set your scan depth to 0 at the settings to continue working with your F/A-18 livery, but it won’t find files out of that specific package folder (they aren’t needed in most cases, though). It should be easy to solve, if it is what I think it is, but I can’t make a promise on the exact time.
Extracting textures is usually a fast process, and the progress bar should bounce to one side and the other. I’ll look into a way of restoring the GUI even if an unexpected error occurs.