`svelte-check` fails when using TypeScript `customConditions` for subpath imports

[xeho91]

Describe the bug

In the project, we use import subpaths in package.json.

In order for TypeScript to work (for tests), we added import condition "development".

Using the following TypeScript config with "customConditions" breaks our CI with svelte-check.

By first glance, I'm not sure if the first errors are misleading. I can't find where our TypeScript config gets overiden:

Caution

Getting Svelte diagnostics...

error TS5098: Option 'customConditions' can only be used when 'moduleResolution' is set to 'node16', 'nodenext', or 'bundler'.

I am not sure if the issue is related to svelte-preprocess, given the error trace paths. I've noticed there's a new version of this one v6. I can't see any connection in CHANGELOG, which would be a possible reference to this issue.

Is there anything that can be done, without necessity to revert usage of subpath imports?

Reproduction

https://github.com/storybookjs/addon-svelte-csf/tree/experimental-support-svelte-v5

Expected behaviour

I expect it to not fail

System Info

macOS 14
Terminal, used CLI svelte-check

Which package is the issue about?

svelte-check

Additional Information, eg. Screenshots

No response

[dummdidumm]

You're hunch is probably right - it's likely a problem of svelte-preprocess forcing the module resolution when it shouldn't.

[xeho91]

I found a possible suspect:
https://github.com/sveltejs/svelte-preprocess/blob/main/src%2Ftransformers%2Ftypescript.ts#L68

Are you able to move this issue to svelte-preprocess?