Formulas that contain markdown characters (e.g. '_' for italic) not rendered correctly

[thilo-behnke]

Hi,

We found the following issue in our project: ls1intum/Artemis#768

E.g. the formula $ a_0 + a_1 $ is not displayed correctly for us, as the html that the extension receives already splits this expression into 3 separate nodes:

0: text -> "$ a"
1: em -> "0 + a"
2: text -> "1 $"

I wonder if the extension should use the type 'lang' instead of 'output', but would be interested in your opinion on this matter:
https://github.com/obedm503/showdown-katex/blob/master/src/showdown-katex.js#L71

[obedm503]

This is because $ are not valid delimiters, use $$ instead. This is an error with the documentation.

Testing in the demo site