Fix 11338

[koppor]

Fixes JabRef#11338

Open points

• Let SnuggleTeX NOT fail on error, but "just" continue (we can accept lost characters)
• Adapt tests to check for .body().text() and not for complete HTML
• Currently, NBSP appears when ~ is rendered. Strange.

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.