fix: remove extra closing brace from caron and ring-above accent templates

[Andrew Avery (AndrewAvery7)]

Problem

A DOCX containing a caron- or ring-accented equation loses every equation in the document, silently, with a zero exit code.

Root cause

In converter_utils/docx/math/latex_dict.py, two entries in CHR carry a fourth closing brace:

"\u030a": "\ocirc{{{0}}}}",   # COMBINING RING ABOVE
"\u030c": "\check{{{0}}}}",   # COMBINING CARON

Every other accent in the table is "\name{{{0}}}". oMath2Latex.do_acc applies these unguarded:

return latex_s.format(c_dict["e"])   # omml.py:213

so both raise ValueError: Single '}' encountered in format string. Of the 46 {0} templates across CHR, CHR_BO, CHR_DEFAULT, POS and POS_DEFAULT, these two are the only ones affected.

The damage is not local to the accented equation. pre_process_docx runs _pre_process_math over the whole of word/document.xml inside a blanket except Exception and, on error, writes the original unprocessed XML back:

try:
    updated_content = _pre_process_math(content)
    zip_output.writestr(name, updated_content)
except Exception:
    # If there is an error in processing the content, write the original content
    zip_output.writestr(name, content)

Mammoth does not render OMML, so every equation in that file disappears from the Markdown. Nothing is logged and the exit code is 0.

Both are standard entries in Word's Equation → Accent gallery, not obscure codepoints.

Reproduction

Using this repository's own tests/test_files/equations.docx, repackaged, then repackaged again with a single caron <m:acc> paragraph appended:

Input	Equations recovered
fixture, unmodified	2
fixture + one caron accent	0
same, with this fix	3 (the original 2, plus $$\check{x}$$)

Fix

Remove the extra brace from both templates.

Tests

Adds tests/test_docx_math_accents.py:

• test_accent_templates_are_formattable — asserts every {0} template in the accent tables survives .format(). This guards the whole table against the same class of typo rather than just these two entries.
• test_caron_and_ring_accents — covers U+030C and U+030A directly.
• test_unmodified_accent_still_converts — control on U+0302, which was never broken.

The first two fail on main and pass with the fix; the control passes either way.

Full suite locally: 322 passed before, 325 after, with the same 14 pre-existing failures in test_cli_vectors.py / test_module_misc.py (Windows console encoding, unrelated to this change) in both runs.

Notes

\ocirc is not standard LaTeX — \mathring is — but neighbouring entries follow the same upstream dwml/STIX naming (\ovhook, \candra, \droang), so I have kept this PR to the brace fix to stay obviously correct rather than mixing in a naming change.

Related: #2188 describes this same symptom (DOCX math converter silently dropping all equations) from a different root cause in do_r; the PRs against it do not touch latex_dict.CHR.

[Andrew Avery (AndrewAvery7)]

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