Unknown node type "body" when compiling MathML in v3.0.1

[hubgit]

Using mathjax-full@3.0.0 it was possible to use this code to convert MathML to SVG:

import { MathML } from 'mathjax-full/js/input/mathml'
import { SVG } from 'mathjax-full/js/output/svg'
import { HTMLAdaptor } from 'mathjax-full/js/adaptors/HTMLAdaptor'
import { HTMLDocument } from 'mathjax-full/js/handlers/html/HTMLDocument'

const doc = new HTMLDocument(document, new HTMLAdaptor(window), {
  InputJax: new MathML(),
  OutputJax: new SVG(),
})

const svg = doc.convert(`<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>A</mi><mo>=</mo></mrow></math>`)

console.log(svg.innerHTML)

Using mathjax-full@3.0.1 an error is thrown when using the same code:

Uncaught Error: Unknown node type "body"
    at MathMLCompile.error (MathMLCompile.ts:320)
    at MathMLCompile.makeNode (MathMLCompile.ts:125)
    at MathMLCompile.compile (MathMLCompile.ts:95)
    at MathML.compile (mathml.ts:145)
    at HTMLMathItem.AbstractMathItem.compile (MathItem.ts:327)
    at Object.renderMath (MathDocument.ts:167)
    at RenderList.renderConvert (MathDocument.ts:211)
    at HTMLMathItem.AbstractMathItem.convert (MathItem.ts:319)
    at HTMLDocument.AbstractMathDocument.convert (MathDocument.ts:633)

It seems to go wrong around this line in MathDocument:

mitem.start.node = this.adaptor.body(this.document)

which sets mitem.start.node to the body of this.document, which suggests that this commit might be to blame.

[dpvc]

Thanks for the report. I can reproduce the problem, and will check into it.

[dpvc]

Your are right, the setting of math.start.node turns out to be the culprit. For the MathML input jax, that node usually points to the MathML node in the document, and its absence meant that the MathML was in math.math as a string that needed to be parsed in order to get the MathML tree. Setting the start node prevented that parsing from being performed, and its content was taken as the MathML itself (the body not that is reported in the error). The start node was being set appropriately for TeX strings, but not MathML strings.

If you use

  InputJax: new MathML({forceReparse: true}),

that should get around the problem for now.

[dpvc]

I've created a pull request to resolve the issue.