no intrinsic metadata as in no corresponding metadata file (eg. pypi: PKG-INFO, npm: package.json).
Both pypi and npm loaders demonstrate that behavior.
Currently, this means the visit fails during ingestion.
By skipping those artifacts, we can have a more complete ingestion
of the impacted origins (providing other artifacts are correctly configured, with their intrinsic metadata file).
[1] https://sentry.softwareheritage.org/share/issue/4a2d3c5f6d4942ddb94a68bb532b6d02/
[2] https://sentry.softwareheritage.org/share/issue/8773eb3140b94675a08143935a61087c/