Raw MathML bug

[zor-el]

I've run into this issue while trying to migrate from Kramdown.

This is the KaTeX output for $E = m c^2$:

<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>E</mi><mo>=</mo><mi>m</mi><mo>⋅</mo><msup><mi>c</mi><mn>2</mn></msup></mrow><annotation encoding="application/x-tex">E = m \cdot c^2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathnormal" style="margin-right:0.05764em;">E</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.4445em;"></span><span class="mord mathnormal">m</span><span class="mspace" style="margin-right:0.2222em;"></span><span class="mbin">⋅</span><span class="mspace" style="margin-right:0.2222em;"></span></span><span class="base"><span class="strut" style="height:0.8141em;"></span><span class="mord"><span class="mord mathnormal">c</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8141em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span></span></span></span></span>

Normally the above snippet would be inserted in the preprocess method of a custom renderer. But even when I paste it into the markdown text directly, it is rendered as

instead of

Redcarpet seems to mistakenly insert one tag as raw text:

The bug seems somehow related to the closing </math> tag. It does not manifest when I insert a space or line break before it. What is weird (to me) is that the tag in question is further down to the closing tag, and not even adjacent to it.

The bug seems somehow related to the caret expression ^2. Inserting a space in any place after it (that doesn't break HTML syntax) - like immediately after ^2 or in between any tag, but before the tag that is treated as raw text (<span class="katex-html" aria-hidden="true">) restores correct rendering.

My workaround is to gsub the Katex output and insert the space programmatically, but it'd be nicer if the issue was properly fixed.

Any takes / ideas / better workarounds?

Thanks a bunch!

[zor-el]

Further investigation shows that the addition of a space anywhere after ^2 restores the correct rendering. Updating the description...