don't except genericache exception

(its error messages have improved)

Author: FynnBe

bioimageio/spec/_internal/io.py

@@ -705,23 +705,19 @@ def _open_url(
         or hashlib.sha256(str(source).encode(encoding="utf-8")).hexdigest()
     )
 
-    try:
-        reader = cache.fetch(
-            source,
-            fetcher=partial(_fetch_url, progressbar=progressbar),
-            force_refetch=digest,
-        )
-    except Exception as e:
-        raise ValueError(f"Failed to fetch {source}.") from e
-    else:
-        return BytesReader(
-            reader,
-            suffix=source_path.suffix,
-            sha256=sha,
-            original_file_name=source_path.name,
-            original_root=source.parent,
-            is_zipfile=None,
-        )
+    reader = cache.fetch(
+        source,
+        fetcher=partial(_fetch_url, progressbar=progressbar),
+        force_refetch=digest,
+    )
+    return BytesReader(
+        reader,
+        suffix=source_path.suffix,
+        sha256=sha,
+        original_file_name=source_path.name,
+        original_root=source.parent,
+        is_zipfile=None,
+    )
 
 
 def _fetch_url(