PyMuPDF hangs when iterating over zero page PDF pages backwards

[C-Saunders]

Description of the bug

PyMuPDF is able to open this PDF, but hangs if I try to iterate over the pages backwards.

How to reproduce the bug

zero_pages.pdf

import pymupdf

pdf = pymupdf.open("...zero_pages.pdf")

# this raises ValueError: bad start page number
for page in pdf.pages():
    print(page.number)

# this hangs forever
for page in pdf.pages(-1, -1):
    print(page.number)

I've tried this on Mac and Linux, and with PyMuPDF versions 1.24.9 and 1.24.13

PyMuPDF version

1.24.13

Operating system

MacOS

Python version

3.11

[JorjMcKie]

Trivial change fixes this.