problem with type-only imports for typescript

[betfix]

I noticed a problem with syntax highlighting, auto-import, svelte-check and Quick Fix options for importing Typescript types.

E.g. for this code

<script lang="ts">
import { Link } from 'svelte-navigator'
export let navigate: NavigateFn
</script> 

1. auto-import
   During typing the word "NavigateFn" intellisense displays a tooltip to auto-import this type from svelte-navigator. The auto-import adds the type to existing import, resulting in:
   import { Link, NavigateFn } from 'svelte-navigator'

2. Quick Fix
   The same happens when choosing a Quick Fix option to add NavigateFn to existing import (this is the only option to choose).

3. syntax highlighting
   All is looking ok inside VSCode, despite adding a compiler option in tsconfig.json:
   "importsNotUsedAsValues": "error"
   Setting this option to "remove" or "preserve" seems to have no impact on VSCode behavior, either.

4. svelte-check
   No error

During runtime there is an error:

SyntaxError: The requested module '/node_modules/.pnpm/[email protected][email protected][email protected]/node_modules/svelte-navigator/src/index.js' does not provide an export named 'NavigateFn'

The expected behavior is to:

1. either display an error inside VSCode and in svelte-check, according to the "importsNotUsedAsValues": "error" typescript setting

2. or make auto-import and Quick Fix use type-only import for types, resulting in code:

import { Link } from 'svelte-navigator'
import type { NavigateFn } from 'svelte-navigator'

[dummdidumm]

The problem is within svelte-preprocess. Since svelte-preprocess only knows the content of the script, it does not know whether something is a type or a value import, so you need to strictly separate them. TypeScript can't help here because it's okay with import as long as there's at least one value import.
See sveltejs/svelte-preprocess#318 for more info and a possible way to fix this.
Keeping this open for visibility

[dummdidumm]

This is fixed with the latest version of svelte-preprocess (you need at least Svelte 3.39 along with it), therefore closing this.