Using 'const' keyword with certain global variables causes mathjax to throw exceptions on render

Created by: applmak

Here's a simple repro case:

<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS_CHTML"></script>
<script>
const scale = 1.0;
</script>
\(x = 1\)

I would expect this to render x = 1, but instead, I see [Math Processing Error].