/game/install.zip already exists

Trying to install a GOG game (Goetia) I get this…

<class ‘shutil.Error’> Destination path ‘/home/allan/.cache/lutris/installer/goetia/unzip’ already exists
File “/home/allan/lutris/lutris/util/jobs.py”, line 30, in target
result = self.function(*args, **kwargs)
File “/home/allan/lutris/lutris/installer/commands.py”, line 180, in extract
extract.extract_archive, filename, dest_path, merge_single, extractor
File “/home/allan/lutris/lutris/installer/commands.py”, line 527, in _killable_process
result = result_obj.get() # Wait process end & reraise exceptions
File “/usr/lib/python3.6/multiprocessing/pool.py”, line 670, in get
raise self._value
…then the installation fails. I have removed and purged everything, reinstalled, but still get the same message. Help please!