[RavSinghChandan]

The outline walk casts /First to a DictionaryObject and subscripts it, so a file where that entry holds a number, a string or an array brings down the whole read:

>>> reader.outline
TypeError: 'NumberObject' object is not subscriptable

The same loop already warns and stops on a cycle, so a node it cannot walk is reported the same way and the read returns what it has. Valid outlines are untouched.

Reverting the change fails the three new tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.01%. Comparing base (39565fe) to head (cd8e9fb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4018   +/-   ##
=======================================
  Coverage   98.00%   98.01%           
=======================================
  Files          57       57           
  Lines       11154    11157    +3     
  Branches     2095     2096    +1     
=======================================
+ Hits        10932    10935    +3     
  Misses        124      124           
  Partials       98       98           

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[stefan6419846]

I have added an inline comment.

Please note that we generally appreciate robustness fixes like these. However, we should avoid having a large number of such similar PRs being worked on in parallel. Given the current number of such PRs, a significant amount of my time is currently going into reviewing them, which makes it harder for me to look into other reported issues and important blockers.

I hope you understand, and that you are able to keep the number of parallel changes at a manageable level. I would prefer not to introduce a strict limit on the number of parallel PRs per contributor, thus I appreciate your help in keeping this manageable.

Additionally, given the relatively large number of previously unreported issues and multiple PRs appearing in close succession, please make sure to follow our contribution guidelines regarding AI usage. I am not trying to imply that you have ignored these guidelines, but some aspects of the current changes raised the question for me, so I would like to make sure we are aligned on this point as well.

[RavSinghChandan]

Added the IDs.

[RavSinghChandan]

1. Use AI to help identify and fix issues.
2. Personally review and test everything before opening a PR.
3. I’ll mention the AI tool and model used in the PR description.
4. I’ll limit my contributions to 1–2 PRs at a time.