Text extraction throws IndexError on some PDFs

[sescobar99]

Recently I ran into a particular kind of pdf file from which I cannot extract text because the library throws an exception.

Environment

Which environment were you using when you encountered the problem?

$ python -m platform
Windows-10-10.0.22621-SP0

$ python -c "import pypdf;print(pypdf._debug_versions)"
pypdf==3.17.0, crypt_provider=('local_crypt_fallback', '0.0.0'), PIL=none

Code + PDF

This is a minimal, complete example that shows the issue:

from pypdf import PdfReader

reader = PdfReader("example.pdf")
number_of_pages = len(reader.pages)
page = reader.pages[0]
text = page.extract_text()
print(text)

Sample PDF file can be found here:
example.pdf

Traceback

This is the complete Traceback I see:

Traceback (most recent call last):
    File "...\prueba_pdf\test.py", line 6, in <module>
        text = page.extract_text()
    File "...\prueba_pdf\venv\lib\site-packages\pypdf\_page.py", line 2284, in extract_text
        return self._extract_text(
    File "...\prueba_pdf\venv\lib\site-packages\pypdf\_page.py", line 1903, in _extract_text
        cmaps[f] = build_char_map(f, space_width, obj)
    File "...\prueba_pdf\venv\lib\site-packages\pypdf\_cmap.py", line 29, in build_char_map
        font_subtype, font_halfspace, font_encoding, font_map = build_char_map_from_dict(
    File "...\prueba_pdf\venv\lib\site-packages\pypdf\_cmap.py", line 54, in build_char_map_from_dict
        map_dict, space_code, int_entry = parse_to_unicode(ft, space_code)
    File "...\prueba_pdf\venv\lib\site-packages\pypdf\_cmap.py", line 224, in parse_to_unicode
        return type1_alternative(ft, map_dict, space_code, int_entry)
    File "...\prueba_pdf\venv\lib\site-packages\pypdf\_cmap.py", line 481, in type1_alternative
        if words[3] != b"put":
IndexError: list index out of range

[sescobar99]

As a matter of fact, I can successfully execute the same code using PyPDF2 (v 3.0.1) and get the proper text extracted.

[Takher]

Looks like a simple fix. Have created the PR here, ready for review.