WARNING: Could not lex literal_block as "jsx". Highlighting skipped.

[stevepiercy]

When I attempt to highlight the following code snippet using Sphinx, MyST, and jsx-lexer, Sphinx returns a warning:

WARNING: Could not lex literal_block as "jsx". Highlighting skipped.

```jsx
import React from 'react';

const View = props => {
  return <div>I'm the Block view component!</div>;
};

export default View;
```

FWIW, if I try js as the lexer, it also does not lex.

See plone/volto#3038

[stevepiercy]

Apparently the lexer does not permit ' within HTML tags. This gets lexed correctly:

import React from 'react';

const View = props => {
  return <div>I am the Block view component!</div>;
};

export default View;

[stevepiercy]

We found another lexer bug.

If I remove aria-label="Cancel", or change it to camel-case as ariaLabel="Cancel", then it gets lexed. However the ReactJS docs specify that kebab-case for ARIA attributes is required.

```jsx
<button className="cancel" aria-label="Cancel" onClick={() => this.onCancel()}>
  <Icon
    name={clearSVG}
    className="circled"
    size="30px"
    title={this.props.intl.formatMessage(messages.cancel)}
  />
</button>
```

[stevepiercy]

I confirm that v2.0 fixes the second example with aria-* attributes, but not the first example with single quotes ' in the text of the HTML tag. I gave it a try but... oof! the JavaScript lexer is a monster!

If only I could figure out how to lex arbitrary HTML tags and their text inside of jsx!