zsh syntax issues with delimiter highlighting

[ev0rtex]

Does this bug happen when you install plugin without vim-polyglot?
No... this is an issue with the syntax additions here for the zsh syntax. Specifically I've narrowed it down to the delimiter customizations in syntax/zsh.vim#L16. Commenting that line out fixes the issue. I don't know much about how vim syntax highlighting works so I'm not sure what the right way to fix it would be.

Describe the bug:
In some of my zsh scripts I have code that uses arithmetic using the $(( ... )) substitution. Whenever I have this and include inner parentheses to group math expressions the rest of the file ends up getting highlighted as a string.

To Reproduce:
The simplest case might be a .zsh file with something like this in it:

somevar="$(( 5 - (4 * 3) ))"
echo "everything after the above line is highlighted as a string"