Error TS4023 when importing types

[webdif]

I have this piece of code:

import { SportsEvent, WithContext } from 'schema-dts';

const getStructuredData = (): WithContext<SportsEvent> => ({
  '@context': 'https://schema.org',
  '@type': 'SportsEvent',
  // ...
});

I have the error TS4023 on this:

Exported variable 'getStructuredData' has or is using name 'SportsEventLeaf' from external module 'myproject/node_modules/schema-dts/dist/schema' but cannot be named

How can I resolve this?

If I modify the schema.d.ts in my node_modules, and I export the SportsEventLeaf interface, it seems to solve this problem. But of course, it's not a real fix…

[Eyas]

Hmm, what TypeScript version are you using? 'Cannot be named' error were much more common in older versions of TS but I thought the checking here was relaxed.

[webdif]

I use TypeScript@3, do you think upgrading TypeScript does the trick?

[Eyas]

It's fixed starting TypeScript 3.9. You can upgrade to 3.9.7 or later.

BTW, if you don't want to upgrade, the fix is to give an explicit type to your function:

 import { SportsEvent, WithContext } from 'schema-dts';

-export const getStructuredData = (): WithContext<SportsEvent> => ({
+export const getStructuredData: ()=>WithContext<SportsEvent> = (): WithContext<SportsEvent> => ({
   '@context': 'https://schema.org',
   '@type': 'SportsEvent',
   // ...
 });

[webdif]

Thank you so much 🙂

[chrisvltn]

This started to happen again.

import {BreadcrumbList} from 'schema-dts';

const data: BreadcrumbList = {'@type': 'BreadcrumbList'};
export const exportedFunction = () => ({data});

Will show the error:

Exported variable 'exportedFunction' has or is using name 'BreadcrumbListLeaf' from external module "..." but cannot be named. ts(4023)

If the function isn't exported, the error seems to not appear, though.