frontend/latex: fix TOC issue and safeguard sync-doc itself

[haraldschilly]

ref #8658

ignore *.toc

sync-doc.ts:1008 Uncaught (in promise) Error: syncstring_table must be defined
    at SyncDoc._this1.syncstring_table_get_one (sync-doc.ts:1008:1)
    at eval (sync-doc.ts:2711:1)
    at step (sync-doc.js:289:23)
    at Object.eval [as next] (sync-doc.js:230:20)
    at asyncGeneratorStep (sync-doc.js:22:28)
    at _next (sync-doc.js:40:17)
    at eval (sync-doc.js:45:13)
    at new Promise (<anonymous>)
    at eval (sync-doc.js:37:16)
    at SyncDoc._this1.handle_syncstring_update (sync-doc.ts:2726:1)

[haraldschilly]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Can't wait for the next one!

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[haraldschilly]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 1aaa6d2374

ℹ️ About Codex in GitHub

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• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

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