Could it be possible that the scene file has been corrupted somehow (the unexpected eof sounds like it)? You can try to open the scene (.tscn file) in text editor (notepad for example) and see if it's alright - you can compare it to some healthy file to look out for suspicious differences especially at the end of the file.
To open scene with Notepad, locate the file in project folder. In Godot, you can right click file and "Show in File Manager". Right click the .tscn file and open with -> more -> Notepad (or something like that, assuming you use Windows). Do make a backup copy if you want to make any changes by hand!