IndexError in MsWordDocumentBackend when processing text without equations

[yssAI]

Bug

When processing certain Word documents (.docx), the handle_text_elements method in msword_backend.py throws an IndexError: list index out of range when attempting to split text that doesn't contain equation markers.

Steps to reproduce

1. Process a Word document containing paragraphs without equation markers (EQ)
2. The error occurs in docling/backend/msword_backend.py, line 380
3. The code assumes all text elements contain equations and tries to split on "EQ"

Docling version

docling 2.28.2
docling-core 2.24.0
docling-ibm-models 3.4.1
docling-parse 4.0.0

Python version

python==3.12.9

In some cases, an extra space in the equation causes an error

[yssAI]

test.docx

You can reproduce this using the docx document in this attachment

[yssAI]

I think I've identified the problem.

The main text is stripped of leading/trailing whitespaces using text.strip(), but the equations array is not processed similarly.

When splitting text_tmp using an equation (eq) as a delimiter, the split fails because eq may contain extra whitespaces that no longer match the stripped text_tmp.

This leads to an IndexError when trying to access text_tmp.split(eq, maxsplit=1)[1] if the split fails to find a match.

[rateixei]

@yssAI Thanks for bringing this up! I had observed this myself and had it in the pipeline. This should be fixed in PR #1268. I'm uploading here the markdown output of your test file.

1284_test.md

[yssAI]

@rateixei The previous document issue was resolved—thanks for the quick fix! However, when testing another DOCX file with the latest fixed code, I still encountered problems. Here’s the document for reference:

38213-i40.docx

[rateixei]

@yssAI Thanks for checking again! This new file was a treasure trove of edge cases which was extremely useful. Please check the export here to see if you spot anything undesired. You can also check this draft PR #1295 for the new logic. If you have any other interesting examples, I'd be happy to take a look!

38213-i40.md

[yssAI]

Thank you for your quick response! My project is still ongoing, so I’ll definitely provide feedback if I run into any other issues. Appreciate your support!