PR 4171 fixes the following errors:

1. OverflowError is raised by seek() for too large offsets of objects or the offset table.

2. Since read() past the file returns b'' and int.from_bytes() used for non-standard sizes accepts b'', bogus offsets and references can be read. This can cause an infinity recursion.

3. The zero size of offsets or references causes ValueError. This is implementation detail.

4. Unicode errors of decoding from invalid ASCII and UTF-8.

It doesn't verify the binary plist, a bogus plist can be successfully parsed to a bogus data. And it doesn't prevent infinity recursion when read cyclic references.