error on user page: error in processing template: ValueError: Invalid seed

[RayBB]

Problem

/openlibrary/openlibrary/templates/lists/snippet.html: error in processing template: ValueError: Invalid seed: Thing(site=<infogami.infobase.client.Site object at 0x7f3053b88050>, key=/works/OL5159916W, data={'location': '/works/OL276798W', 'key': '/works/OL5159916W', 'type': Thing(site=<infogami.infobase.client.Site object at 0x7f3053b88050>, key=/type/redirect, data=None, revision=None), 'latest_revision': 9, 'revision': 9, 'created': datetime.datetime(2009, 12, 10, 8, 51, 6, 587414), 'last_modified': datetime.datetime(2021, 4, 14, 13, 29, 27, 506)}, revision=None) (falling back to default template)

Evidence / Screenshot

Relevant URL

https://openlibrary.org/people/clh7cb

Reproducing the bug

1. Go to the page

• Expected behavior: no error
• Actual behavior: there is an error

Context

• Browser (Chrome, Safari, Firefox, etc): FF
• OS (Windows, Mac, etc): Mac
• Logged in (Y/N): Y
• Environment (prod, dev, local): prod

⚠️ Experienced contributors only

Proposal & constraints

Related files

Stakeholders

[cdrini]

@scottbarnes and I did a preliminary analysis ; this seems to be a sporadic error.

This is the underlying error:

Our current hypothesis is that this only errors when a cache miss happens, and the user's list contains a redirect.

It seems like under these conditions, the seed is returned as a client.Thing instead of the openlibrary subclass of client.Thing, which is what is checked for on line 403 in the image above.