Svelte for VSCode: preprocessor: `preserve: ["ld+json"]` in config doesn't fix red squiggles in component script

[jthistle]

Describe the bug
When attempting to include <script type="application/ld+json"> in <svelte:head>, red underlines appear in the component <script>, even though Svelte compiles the application without complaints and the configuration is correctly set up.

Before I added the preserve option to the configuration, I was also getting the same red squiggles, but Svelte was also complaining and would not compile the file, so the squiggles were expected.

To Reproduce
Minimal example:

svelte.config.js:

// svelte.config.js:
const sveltePreprocess = require('svelte-preprocess');

function createPreprocessors(sourceMap) {
    return sveltePreprocess({
        sourceMap,
        preserve: ["ld+json"],
    });
}

module.exports = {
    preprocess: createPreprocessors(true),
    createPreprocessors
};

rollup.config.js:

// ...
const { createPreprocessors } = require('./svelte.config');

export default {
	// ...
	plugins: [
		svelte({
			preprocess: createPreprocessors(true),
			// ...
		}),
		// ...
	],
	// ...
}

Component.svelte:

<script>
    const schema = {
        key: "value",
        // ^ red squiggles appear here
    };
</script>

<svelte:head>
    {@html `<script type="application/ld+json">${JSON.stringify(schema)}</script>`} <!-- *** -->
</svelte:head>

Note that commenting out the line marked with <!-- *** --> fixes the problem.

Expected behavior
No red squiggles appear, everything is fine in the eyes of the language server.

System (please complete the following information):

• OS: Ubuntu 20.04 LTS
• IDE: VSCode
• Plugin/Package: Svelte for VSCode

[jthistle]

Workaround:

in Component.svelte, escape the closing / in the template string and move it to the main script body:

<script>
    const schema = {
        key: "value",
    };

    const schemaHtml = `<script type="application/ld+json">${JSON.stringify(schema)}<\/script>`;
</script>

<svelte:head>
    {@html schemaHtml}
</svelte:head>

It seems the language server just doesn't like the </script> tag within the @html directive.