raise on snapshot download

Signed-off-by: Ian Eaves <[email protected]>

Author: ieaves

ramalama/model_store/store.py

@@ -187,6 +187,8 @@ def _prepare_new_snapshot(self, model_tag: str, snapshot_hash: str, snapshot_fil
 
     def _download_snapshot_files(self, model_tag: str, snapshot_hash: str, snapshot_files: Sequence[SnapshotFile]):
         ref_file: None | RefJSONFile = self.get_ref_file(model_tag)
+        if ref_file is None:
+            raise ValueError("Cannot download snapshots without a valid ref file.")
 
         for file in snapshot_files:
             dest_path = self.get_blob_file_path(file.hash)
@@ -197,7 +199,7 @@ def _download_snapshot_files(self, model_tag: str, snapshot_hash: str, snapshot_
                 if file.required:
                     raise ex
                 # remove file from ref file list to prevent a retry to download it
-                if ex.code == HTTPStatus.NOT_FOUND and ref_file:
+                if ex.code == HTTPStatus.NOT_FOUND:
                     ref_file.remove_file(file.hash)
                 continue
 
@@ -217,8 +219,7 @@ def _download_snapshot_files(self, model_tag: str, snapshot_hash: str, snapshot_
                 os.symlink(blob_relative_path, link_path)
 
         # save updated ref file
-        if ref_file:
-            ref_file.write_to_file()
+        ref_file.write_to_file()
 
     def _ensure_chat_template(self, model_tag: str, snapshot_hash: str, snapshot_files: list[SnapshotFile]):
         model_file: SnapshotFile | None = None