IndexError on empty strong mark on version 2024.2.25

[elmernocon]

• html2text 2024.2.25
• Python 3.9+

• Test script

  ✅ default

  converter = html2text.HTML2Text()
  converter.emphasis_mark = "_"
  converter.strong_mark = "**"
  string = "A <b>B</b> <i>C</i>."
  result = converter.handle(string)
  print(result)
  # output: A **B** _C_.

  ✅ emphasis emptied ''

  converter = html2text.HTML2Text()
  converter.emphasis_mark = ""
  converter.strong_mark = "**"
  string = "A <b>B</b> <i>C</i>."
  result = converter.handle(string)
  print(result)
  # output: A **B** C.

  ❌ strong emptied ''

  converter = html2text.HTML2Text()
  converter.emphasis_mark = "_"
  converter.strong_mark = ""
  string = "A <b>B</b> <i>C</i>."
  result = converter.handle(string)
  print(result)
  # expected output: A B _C_.

  Traceback (most recent call last):
    File "script.py", line 29, in <module>
      main()
    File "script.py", line 24, in main
      result = converter.handle(string)
    File "test/venv/lib/python3.9/site-packages/html2text/__init__.py", line 145, in handle
      self.feed(data)
    File "test/venv/lib/python3.9/site-packages/html2text/__init__.py", line 141, in feed
      super().feed(data)
    File "/opt/homebrew/Cellar/python@3.9/3.9.18_1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/html/parser.py", line 110, in feed
  self.goahead(0)
    File "/opt/homebrew/Cellar/python@3.9/3.9.18_1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/html/parser.py", line 170, in goahead
      k = self.parse_starttag(i)
    File "/opt/homebrew/Cellar/python@3.9/3.9.18_1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/html/parser.py", line 344, in parse_starttag
      self.handle_starttag(tag, attrs)
    File "test/venv/lib/python3.9/site-packages/html2text/__init__.py", line 194, in handle_starttag
      self.handle_tag(tag, dict(attrs), start=True)
    File "test/venv/lib/python3.9/site-packages/html2text/__init__.py", line 441, in handle_tag
      and self.preceding_data[-1] == self.strong_mark[0]
  IndexError: string index out of range

[Alir3z4]

Thanks for the report. https://github.com/Alir3z4/html2text/pull/410 should fix it.

I'll merge and publish a new release tomorrow.