(feat) detect invalid Svelte import paths

[dummdidumm]

Detect that an import of a .svelte file is pointing to a non-existent file by removing the ambient module definitions in svelte and svelte2tsx from the eyes of TS.

If you want the old behavior back, add a ambient.d.ts file (or similar; you can add it to app.d.ts in a SvelteKit project for example) with the following:

declare module "*.svelte";

#1444

@jasonlyu123 please tell me if this too hacky or actually a good idea 😅

[jasonlyu123]

I am ok with this.

Alternatively, we can also add the error by ourselves. We could use the type-checker to get the symbol of the ImportDeclartion.moduleSpecifier. And see if the symbol name is "*.svelte" or if the declaration is from the two files. But to turn this into a diagnostic message. We need to either use typescript internal APIs or copy the error message and other info. So it's also kind of hacky. And we still need to filter out the *.svelte hover or completion.

[dummdidumm]

Yeah, I feel that this would be just as hacky and more code - ok, I'll merge this then, thanks for your insights!

[DetachHead]

@dummdidumm thanks for fixing this! one question though, is this change supposed to only effect the behavior in vscode's intellisense? as the ambient.d.ts module is still present in the svelte package so when i run svelte-check it still has the old behavior