Object of type 'PSKeyword' has no len() via cmapdb.py

[Irina-Pavlova]

          I have the same issue for some PDFs (which unfortunately contain sensitive information). 

The version of pdfminer.six I'm using is 20221105.
My bug report is like below, from issue #617

File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/high_level.py", line 200, in extract_pages
interpreter.process_page(page)
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdfinterp.py", line 991, in process_page
self.render_contents(page.resources, page.contents, ctm=ctm)
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdfinterp.py", line 1010, in render_contents
self.execute(list_value(streams))
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdfinterp.py", line 1036, in execute
func(*args)
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdfinterp.py", line 896, in do_TJ
self.device.render_string(
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdfdevice.py", line 133, in render_string
textstate.linematrix = self.render_string_horizontal(
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdfdevice.py", line 170, in render_string_horizontal
for cid in font.decode(obj):
File "/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/pdffont.py", line 1174, in decode
return self.cmap.decode(bytes)
File "~/.virtualenvs/foo/lib/python3.10/site-packages/pdfminer/cmapdb.py", line 134, in decode
n = len(code) // 2
TypeError: object of type 'PSKeyword' has no len()

_Originally posted by @cchristiansen in https://github.com/pdfminer/pdfminer.six/issues/617#issuecomment-1135787678_
            

A quick hack which fixes the issue for me, is to insert the following two lines into `cmapdb.py` at line 134:

            if isinstance(code, PSKeyword):
                code = code.name

Could your please fix this? Thanks in advance

[dhdaines]

This is a consequence of #1042 - we declare (in the type annotations which are not checked at runtime) that code is a bytes, but in reality, some code further up the chain has decided that because in a compliant PDF, the argument to a text showing operator (except TJ) can only be a bytes , then, well, it is obviously a bytes, and doesn't need to be checked at runtime.

This is obviously not true :)