Update src/hyp3_sdk/jobs.py

Co-authored-by: Jake Herrmann <[email protected]>

src/hyp3_sdk/jobs.py

@@ -138,7 +138,7 @@ def download_files(self, location: Path | str = '.', create: bool = True) -> lis
         elif not location.is_dir():
             raise NotADirectoryError(str(location))
 
-        assert isinstance(self.files, list)
+        assert self.files is not None
 
         downloaded_files = []
         for file in self.files: