Kodak Capture Desktop and probably other software creates a
/Outlines entry with /First being set to an invalid indirect reference to
an object that hasn't been created. This is legal in the PDF spec but
problematic for qpdf. The objgen will be (max valid object ID + 1, 0).
Because we create new objects in _weave, some TOC entries will end
up assigned to new objects we create. Typically /ProcSet.
We solve the issue by refactoring page traversal and then doing it
twice, once to resolve all references (eliminating the null
reference problem) and a second pass to make our changes.
For some reason PyPDF2 has begun to trigger internal errors in
pytest on macOS alone. Not sure why, but nothing is wrong that I can
see. Seemed like an opportune time to switch to pikepdf; found some
new issues in the process anyway.
Related to previous validation issue. If the /CreationDate had no
timezone, Ghostscript also creates invalid metadata. Work around this.
Also fix up PDF date decoding, and transcode dates to standardize them.
James R. Barlow