`$\newcommand{\foo}{bar}$` renders as "$$"

[cben]

I expected empty rendering (suboptimal, #10) or visible "$\newcommand{\foo}{bar}$" but not just the dollars.
What happens is my \newcommand visibility special casing sends this to MathJax:

$\newcommand{\foo}{bar}$ \($\newcommand{\foo}{bar}$\)

The intent was that the first part be visible while the would be processed by mathjax, but in this case both are processed and the dollars in the second part are visible.