ROB: Fix errors/warnings on no /Resources within extract_text

[pubpub-zz]

fix #1272 (in text) and #1269 (in Xform)

[codecov]

Codecov Report

Merging #1276 (a4feaba) into main (ceb997d) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1276   +/-   ##
=======================================
  Coverage   95.02%   95.03%           
=======================================
  Files          30       30           
  Lines        4968     4974    +6     
  Branches     1023     1024    +1     
=======================================
+ Hits         4721     4727    +6     
  Misses        140      140           
  Partials      107      107           

Impacted Files	Coverage Δ
PyPDF2/_page.py	93.99% <100.00%> (+0.06%)	⬆️

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[MartinThoma]

Thank you for the PR @pubpub-zz 🤗

[MartinThoma]

According to TABLE 3.27 Entries in a page object in the PDF 1.7 specs, the /Resources is required:

(Required; inheritable) A dictionary containing any resources required by
the page (see Section 3.7.2, “Resource Dictionaries”). If the page requires
no resources, the value of this entry should be an empty dictionary. Omit-
ting the entry entirely indicates that the resources are to be inherited from
an ancestor node in the page tree.

As it is required, I would throw an exception in strict mode and a logger_warning otherwise.

Do you know if we handle the inheritance case? From what can it be inherited?

[pubpub-zz]

I've added some code to check in the parents. But if not present. I do not think it worth to check that Tj or TJ is present in the content (it will complexify the code with very limited interest)
if somebody exhibits a file showing this case, we can add the test at that time