I have begun isolating the problem parts,
and will now iterate through them, deregistering
the packages from doc-base to try and get a successful
run.
The output from the second index run, after having
taken out the successul parts, is as follows:
Processing 02.part
Error decompressing file: /usr/share/debian-reference/debian-reference.en.txt.gz
Processing 04.part
Error decompressing file: /usr/share/doc/base-passwd/users-and-groups.txt.gz
Error decompressing file: /usr/share/doc/debian/bug-reporting.txt.gz
Error decompressing file: /usr/share/doc/debian/constitution.txt.gz
Processing 05.part
Error decompressing file: /usr/share/doc/exim4-base/filter.txt.gz
Error decompressing file: /usr/share/doc/exim4-base/spec.txt.gz
Processing 07.part
Error decompressing file: /usr/share/doc/java-common/policy.txt.gz
Processing 08.part
Error decompressing file: /usr/share/doc/libpng12-0/libpng-1.2.50.txt.gz
Processing 11.part
Error decompressing file: /usr/share/doc/python/python-policy.txt.gz
Error converting file: /usr/share/doc/qpdf/qpdf-manual.pdf
Error converting file: /usr/share/doc/shared-mime-info/shared-mime-info-spec.pdf
Processing 13.part
Error decompressing file: /usr/share/doc/xterm/ctlseqs.txt.gz