chore: move typescript to svelte-check's peer dependency

[Andarist]

It is kinda debatable but I feel that it's better to use the installed version of typescript. I just had to go through a surprising debugging session since my IDE was using TypeScript 4.8 but svelte-check was using TypeScript 4.5 (I had an old version that had the * range declared on typescript and TS 4.5 was left in the lockfile from before the rest of the monorepo bumped TS to TS 4.8.

I understand that this might create a different problem though - now the svelte-check might run with a different version of TS than the VS Code extension. However, this isn't a new problem - it already exists.

[dummdidumm]

I'm very hesitant to merge this. Having it as a peer dependency allows us to make use of new TypeScript constructs without having to release a major version svelte-check. It doesn't happen often but it did before.

[Andarist]

From my PoV it's important to consider user expectations here.

Scenario 1:

1. I upgrade my project to TS 5.0 (the version itself doesn't really matter, it's just an example) and I start using const type parameters
2. Can I expect svelte-check to handle this new syntax? And this isn't even about new syntax - any TS version can change the type checking behavior. Is it expected that I don't get any errors when running tsc or in the IDE (in my regular TS files) or is it expected that I can run into problems here? Is this caveat communicated in the docs anyhow?

Scenario 2:

1. I upgrade svelte-check and it starts using TS 5.0 with its more strict relational operators
2. Is it expected that I start getting new errors for the existing code only when running through svelte-check?

without having to release a major version svelte-check

What's the problem with new major versions though? They are honest and convey the intent nicely. It's just like an age - it's just a number 😉

[DavidArchibald]

I can second that I ran into this problem and it was an annoying surprise. I was going to file this as an issue myself!

For others running into this, I ended up solving this by adding this to my package.json file

    "resolutions": {
        "typescript": "^5.5.4"
    }

But it was only after I digged into the source itself that I realised it was bundling the TypeScript version and just about filed an issue myself.

[benmccann]

This should be updated to allow Typescript 5 to be used as well

Suggested change

	"typescript": "^4.9.0"
	"typescript": ">=4.9.0"

[dummdidumm]

Closing in favor of #2453