LaTeX-Workshop: Hover equation preview fails with confusing error

Disable all the other extensions except for LaTeX Workshop, and check that you still see this issue. [Required]

You still see this issue?: Yes

Describe the bug [Required] I understand there is a hover equation preview feature. I have never witnessed this working on my computer, but I do see errors in the logs when I hover over an equation. Unfortunately the error is not helpful in diagnosing the problem. I am sure the error is due to some problem in my system or configuration, of course! However, I cannot work out what it would be.

To Reproduce Steps to reproduce the behavior:

1. create a minimal document, such as the following

\documentclass{article}

\title{Topics in stochastic processes}
\author{Daniel MacKinlay}
\date{2019}


\begin{document}

\maketitle

\[x\]

\end{document}

1. Mouse over the \[x\]

Expected behavior A hover should appear showing the letter x typeset as a display math equation

Actual behavior No hover appears. errors appear in the extension host logs

Logs [Required] Please paste the whole log messages here, not parts of ones. It is very important to identify problems. If you think the logs are unrelated, please say so.

LaTeX Workshop Output [Required]

n/a

Developer Tools Console [Required]

[Extension Host] Error when JSON.parse theme files. console.ts:137 [Extension Host] Unexpected token ] in JSON at position 3948 console.ts:137 [Extension Host] TeX parse error: Extra close brace or missing open brace t.log @ console.ts:137 log.ts:196 ERR TeX parse error: Extra close brace or missing open brace

Extention host log

[2019-11-12 18:43:59.757] [exthost] [error] [James-Yu.latex-workshop] provider FAILED [2019-11-12 18:43:59.757] [exthost] [error] ["TeX parse error: Extra close brace or missing open brace"]

Desktop [Required]:

• OS: Ubuntu 18.04
• VS Code version:1.40.0
• Extension version: 8.3.1

Are you using LaTeX Workshop with VS Code Remote?

No

Additional context