Tree view appears to have some trouble with JSX when using Recast

**Describe the bug**
First off, a HUGE thank you for making this project available. It's been so incredibly helpful!

I appear to have broken the tree view and code when attempting to using JSX syntax in conjunction with recast.

Instead of displaying the super-helpful AST viewer, the tree view prints an error message like this: `Invalid regular expression: missing /`.

It seems some of the `recast` configuration may be misidentifying a closing JSX tag with a regular expression.

When switching to a different parser (ex: `babylon7`), the tree view displays as expected.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to the example [gist](https://astexplorer.net/#/gist/8a86c88a37143c3548397f606479ad06/601540198f013661ad5aa03a5038ac6186b197a9) to replicate the bug.
2. Examine the "Tree" tab of the AST Viewer
3. See error message `Line 4: Invalid regular expression: missing /`

**Expected behavior**
The interactive AST display rendered as it does with vanilla JavaScript.

**Screenshots**
Here's the state of the code editor:

**Browser (please complete the following information):**
- OS: macOS 10.14.6
- Browser: Brave (Chromium browser)
- Version: (Brave) 0.68.138 Chromium: 77.0.3865.75 (Official Build) (64-bit)

**astexplorer settings:**
- Selected parser: `recast` configured to use `babylon7`
- Selected transformer (if applicable): `jscodeshift`
- Contents of the local storage key `explorerSettingsV1`
```
{"showTransformPanel":false,"parserSettings":{},"parserPerCategory":{},"workbench":{"parser":"acorn","code":"/**\n * Paste or drop some JavaScript here and explore\n * the syntax tree created by chosen parser.\n * You can use all the cool new features from ES6\n * and even more. Enjoy!\n */\n\nlet tips = [\n \"Click on any AST node with a '+' to expand it\",\n\n \"Hovering over a node highlights the \\\n corresponding part in the source code\",\n\n \"Shift click on an AST node expands the whole substree\"\n];\n\nfunction printTips() {\n tips.forEach((tip, i) => console.log(`Tip ${i}:` + tip));\n}\n","keyMap":"default","transform":{"code":"","transformer":null}}}
```

**Additional context**
The code editor *also* seems to have a syntax highlighting problem with the closing tag as well, so the issue with JSX may not be entirely limited to the AST Tree viewer