Can’t use double backslash as `children` in components

[Paalon]

Describe the bug

Can’t use double backslash \\ in the following code:

https://svelte.dev/playground/333ee16c4786473cada88079151bb6db?version=5.22.6

<-- App.svelte -->
<script>
	import Sample from "./Sample.svelte";
</script>

<Sample>Hello!</Sample>

<Sample>\\</Sample>

<-- Sample.svelte -->
<script>
	const { children } = $props();
</script>

<span>{@render children()}</span>

in the following situation:

"devDependencies": {
		"@sveltejs/adapter-auto": "^4.0.0",
		"@sveltejs/kit": "^2.16.0",
		"@sveltejs/vite-plugin-svelte": "^5.0.0",
		"@tailwindcss/vite": "^4.0.0",
		"svelte": "^5.0.0",
		"svelte-check": "^4.0.0",
		"tailwindcss": "^4.0.0",
		"typescript": "^5.0.0",
		"vite": "^6.0.0"
	}

I can’t show the original project that I found the error but I encountered the following error message:

9:37:02 PM [vite] (client) Pre-transform error: Failed to parse source for import analysis because the content contains invalid JS syntax. If you are using JSX, make sure to name the file with the .jsx or .tsx extension.
  Plugin: vite:import-analysis

and the playground’s minimal reproduction sample emits the following error:

Error compiling component

./App.svelte (36:23): Unterminated string constant (Note that you need plugins to import files that are not JavaScript)

Reproduction

Showed in the above and the playground.

Logs

Showed in the above and the playground.

System Info

System:
    OS: macOS 15.3.1
    CPU: (8) arm64 Apple M3
    Memory: 87.41 MB / 24.00 GB
    Shell: 4.0.0 - /opt/homebrew/bin/fish
  Binaries:
    Node: 23.9.0 - /opt/homebrew/bin/node
    npm: 10.9.2 - /opt/homebrew/bin/npm
  Browsers:
    Safari: 18.3
  npmPackages:
    svelte: ^5.0.0 => 5.22.6

Severity

Blocking my transition from React to Svelte 5

[jdkdev]

Tried updating from 5.16 to 5.23 and, I am using markdown and my single slashes are maybe? escaped to double slashes and then getting the same issue.

Here is the md file, and I'm using mdsvex:

I believe is it just the trailing slash that is causing issues.