Errors in `app.d.ts` are not checked and/or detected

[205g0]

Describe the bug

Pretty much the title and it happens always after refactorings because app.dt.s isn't refactored

Reproduction

Try a broken import, e.g. import { nonsense ) from '$lib/lol'.

FWIW, I have below declare global { ... } wrapping declare namespace App.

Expected behaviour

squiggle line below the broken import

System Info

• OS: WSL2 with Ubuntu 22.04
• IDE: VS Code

Which package is the issue about?

No response

Additional Information, eg. Screenshots

No response

[jasonlyu123]

You probably have skipLibCheck enabled. SvelteKit has it by default. Enabling it might cause typescript to spend a lot more time checking .d.ts files inside your node_modules when running tsc or svelte-check. And there isn't an option to disable lib check only for node_modules. You can enable it while you're making sure the file doesn't have an error and disable it when you're done.

[jasonlyu123]

Actually, You can rename it to app.ts and it'll be checked. You won't normally need to write stuff in app.d.ts that needs to be written with declaration file syntax anyway.

[205g0]

Ok, sounds like a plan, however I couldn't rewrite app.d.ts to app.ts without gazillions of type error throughout my codebase or eslint driving nuts in app.ts

I checked a few sources how to migrate from declare to without and asked ChatGPT but it doesn't look trivial or I need more time...

[205g0]

following works with tsserver as app.ts but not eslint ('ES2015 module syntax is preferred over namespaces.eslint') and I still need declare:

declare global {
  namespace App {
    interface Locals {
       ...
    }
    ...
  }

  namespace svelteHTML {
    interface HTMLAttributes {
      ....
    }
  }
}

[205g0]

this works with eslint but not with tsserver which shows tons of errors:

declare global {
  export interface Locals {
    ...
  }

  export interface HTMLAttributes {
    ...
  }
}

[jasonlyu123]

You can disable the namespace rule for that file or per line since it has to be like this. Or add app.ts to .eslintignore

[205g0]

ok thanks, I added it to .eslinttc.cjs since VS Code didn't pick up .eslintignore for whatever reason

out of curiosity, why do we need to manually add type defs to app.d.ts (now app.ts) why can't SK not infer e.g. Locals from hooks.servrer.ts (i mean import them from there or an intermediate file anyway)? or do i miss something?

[dummdidumm]

app.d.ts types defines the contract that both the handle hook and its usage locations need to adhere to - that way made more sense to use compared to infering it from the hook. It's also next to impossible to infer the type because it's not returned from the handle hook.

Closing as the questions have been answered.