Custom syntax highlighter is never called

[illright]

Steps to reproduce:

• Clone the Svelte template
• Install mdsvex: yarn add -D mdsvex
• Set up MDsveX in rollup.config.js:

// ...
import { mdsvex } from 'mdsvex';

export default {
  // ...
  plugins: [
    // ...
    svelte({
      extensions: ['.svelte', '.svx'],
      preprocess: mdsvex({
        highlight(code, _lang) {
          console.log('called');
          return `<pre>${code}</pre>`;
        }
      }),
    }),
// ...

• Add an MDsveX file (src/test.svx) with the following content:

```js
alert()

* Import the new file into `src/App.svelte`

## Expected

`called` will be printed anywhere signifying that the highlighter was called

## Actual

Nothing printed, the default highlighter is used

Also I'm wondering if there's any simple way of stripping the initial newline that is rendered in the `<pre>`

[pngwn]

Looks like I didn't update the docs. Highlight should be an object that accepts a highlighter property:

// ...
import { mdsvex } from 'mdsvex';

function highlighter(code, _lang) {
  console.log('called');
  return `<pre>${code}</pre>`;
}

export default {
  // ...
  plugins: [
    // ...
    svelte({
      extensions: ['.svelte', '.svx'],
      preprocess: mdsvex({
        highlight: { highlighter }
      }),
    }),
// ...

I'll update the documentation.

Can you give an example for the initial newline you mentioned?

[illright]

The example for the issue would be the default configuration. Follow the same reproduction steps, but don't override the highlighter. Then the code from test.svx will be rendered in a <pre> element spanning two lines, the first line being just a linefeed and the second containing actual code

[TheComputerM]

It looks like this:

```js console.log('hello there') console.log('general kenobi') ```

The default settings were used

https://svelte-materialify.netlify.app/components/buttons/ The SVX file

[TheComputerM]

And the docs are still not updated

[pngwn]

Fixed in #110.

Thanks @TheComputerM!