OK, that's a bug but not a regression. cf https://www.mediawiki.org/wiki/Extension:Math/T183559

A re-run of the erroneous requests revealed that there are ~15k formulae that pass the check but fail to render due to various errors. We should investigate the reasons of the incompatibility between texvcinfo and MathJax since the expectation should be that if a formula passes the check, we should be able to render it as well. I'm attaching two files for inspection:

• render_new.yaml contains the formulae and the respective errors for cases where Mathoid v0.7.0 fails to render it, but the previous version was able to do so; and
• render_both.yaml contains formulae that both the new and the old Mathoid fail to render

I checked the render both cases with texvcjs. They all pass the tests even though they contain non valid latex characters. cf. https://github.com/physikerwelt/texvcjs/tree/invalid-input. I guess that the text field misses a rule that specifies which characters are supported by TeX or MathJax respectively.

While rendering the formulae that previously failed the check (14k of them), 202 failed to render only with the new Mathoid, and 681 of them failed to render both with the old and new versions: