MarkdownTextSplitter: multiple repeat at position 4 (line 3, column 2)

[communiteq]

System Info

langchain 0.0.188
python 3.8.10

Who can help?

No response

Information

• The official example notebooks/scripts
• My own modified scripts

Related Components

• LLMs/Chat Models
• Embedding Models
• Prompts / Prompt Templates / Prompt Selectors
• Output Parsers
• Document Loaders
• Vector Stores / Retrievers
• Memory
• Agents / Agent Executors
• Tools / Toolkits
• Chains
• Callbacks/Tracing
• Async

Reproduction

from langchain.docstore.document import Document
from langchain.text_splitter import MarkdownTextSplitter

# of course this is part of a larger markdown document, but this is the minimal string to reproduce
txt = "\n\n***\n\n" 

doc = Document(page_content=txt)
markdown_splitter = MarkdownTextSplitter(chunk_size=1000, chunk_overlap=0)
splitted = markdown_splitter.split_documents([doc])

Traceback (most recent call last):
  File "t.py", line 9, in <module>
    splitted = markdown_splitter.split_documents([doc])
  File "/home/richard/.local/lib/python3.8/site-packages/langchain/text_splitter.py", line 101, in split_documents
    return self.create_documents(texts, metadatas=metadatas)
  File "/home/richard/.local/lib/python3.8/site-packages/langchain/text_splitter.py", line 88, in create_documents
    for chunk in self.split_text(text):
  File "/home/richard/.local/lib/python3.8/site-packages/langchain/text_splitter.py", line 369, in split_text
    return self._split_text(text, self._separators)
  File "/home/richard/.local/lib/python3.8/site-packages/langchain/text_splitter.py", line 346, in _split_text
    splits = _split_text(text, separator, self._keep_separator)
  File "/home/richard/.local/lib/python3.8/site-packages/langchain/text_splitter.py", line 37, in _split_text
    _splits = re.split(f"({separator})", text)
  File "/usr/lib/python3.8/re.py", line 231, in split
    return _compile(pattern, flags).split(string, maxsplit)
  File "/usr/lib/python3.8/re.py", line 304, in _compile
    p = sre_compile.compile(pattern, flags)
  File "/usr/lib/python3.8/sre_compile.py", line 764, in compile
    p = sre_parse.parse(p, flags)
  File "/usr/lib/python3.8/sre_parse.py", line 948, in parse
    p = _parse_sub(source, state, flags & SRE_FLAG_VERBOSE, 0)
  File "/usr/lib/python3.8/sre_parse.py", line 443, in _parse_sub
    itemsappend(_parse(source, state, verbose, nested + 1,
  File "/usr/lib/python3.8/sre_parse.py", line 834, in _parse
    p = _parse_sub(source, state, sub_verbose, nested + 1)
  File "/usr/lib/python3.8/sre_parse.py", line 443, in _parse_sub
    itemsappend(_parse(source, state, verbose, nested + 1,
  File "/usr/lib/python3.8/sre_parse.py", line 671, in _parse
    raise source.error("multiple repeat",
re.error: multiple repeat at position 4 (line 3, column 2)

Expected behavior

splitted contains splitted markdown and no errors occur