KaTeX math problem for hard-tab-indented equation with linebreak

This works correctly:
```markdown
1. text
$$\begin{bmatrix}
a,b
\end{bmatrix}$$
```
But if we use hard tabs (i.e. `\t`) instead of spaces for indentation, the equation is not correctly displayed. What's more, if we write the equation in a single line (i.e. no linebreak between two `$$`'s), it works correctly again, even with hard-tabs.