The option 'family' for tex2svg / tex2chtml has no default value

Created by: christianp

I use MathJax.getMetricsFor to get an options object for tex2chtml or tex2svg, as described in the typesetting page in the docs.

It includes an attribute family whose value is the empty string. When I pass the object to tex2chtml, I get an error "Invalid option "family" (no default exists)". So it looks easy to fix, but I don't know where to look for the default values.

Here's a node script which produces the error:

const MathJax = require('mathjax');

MathJax.init({
    loader: {load: ['input/tex', 'output/svg']}
}).then(MathJax => {
    const svg = MathJax.tex2svg('2x',{family:''});
}).catch(err => {
    console.error(err);
});

(I'd love to fix this myself, but I can't remember how to run unminified MathJax v3)