Errors linked to #274

[LysandreJik]

Since #274 was merged, we've been getting errors in the transformers CI:

(https://huggingface.slack.com/archives/D027SQ7S3PW/p1661254790289019)
Traceback (most recent call last):
  File "/usr/local/bin/doc-builder", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/site-packages/doc_builder/commands/doc_builder_cli.py", line 47, in main
    args.func(args)
  File "/usr/local/lib/python3.8/site-packages/doc_builder/commands/push.py", line 202, in push_command
    deletions = create_deletions(args.doc_build_repo_id, args.library_name, args.token)
  File "/usr/local/lib/python3.8/site-packages/doc_builder/commands/push.py", line 97, in create_deletions
    tree = json["tree"]
KeyError: 'tree'

See https://github.com/huggingface/transformers/runs/7972055522?check_suite_focus=true

cc @mishig25