Handle config.json not found (image models)

src/exo/download/download_utils.py

@@ -457,6 +457,8 @@ async def download_file_with_retry(
             )
         except HuggingFaceAuthenticationError:
             raise
+        except FileNotFoundError:
+            raise
         except HuggingFaceRateLimitError as e:
             if attempt == n_attempts - 1:
                 raise e

src/exo/master/api.py

@@ -386,7 +386,12 @@ class API:
         if len(list(self.state.topology.list_nodes())) == 0:
             return PlacementPreviewResponse(previews=[])
 
-        model_card = await ModelCard.load(model_id)
+        try:
+            model_card = await ModelCard.load(model_id)
+        except Exception as exc:
+            raise HTTPException(
+                status_code=400, detail=f"Failed to load model card: {exc}"
+            ) from exc
         instance_combinations: list[tuple[Sharding, InstanceMeta, int]] = []
         for sharding in (Sharding.Pipeline, Sharding.Tensor):
             for instance_meta in (InstanceMeta.MlxRing, InstanceMeta.MlxJaccl):