Effect CommunityEC
Effect Community•16mo ago
Aurélien (quasar.work)

Error Extending `Data.TaggedError` Class in TypeScript

I have a weird issue.

Since the Data.TaggedError itself cannot be extended the way I want because of TS4023: Exported variable X has or is using name Y from external module, I tried to copy/paste the code from the Effect repository.

However, even when leaving the code untouched:
/**
 * Original Data.TaggedError class can be found here:
 *
 * @see https://github.com/Effect-TS/effect/blob/35a0f813141652d696461cd5d19fd146adaf85be/packages/effect/src/Data.ts#L552
 */
const ErrorBase = <Tag extends string>(
  tag: Tag,
): new <A extends Record<string, any> = {}>(
  args: Types.Equals<A, {}> extends true
    ? void
    : { readonly [P in keyof A as P extends "_tag" ? never : P]: A[P] },
) => Cause.YieldableError & { readonly _tag: Tag } & Readonly<A> => {
  class Base extends Error<{}> {
    readonly _tag = tag;
  }

  (Base.prototype as any).name = tag;
  return Base as any;
};


I get a:
Error: BUG: FiberRuntime - {

How in the world is it working when I import it from the package, but fails to work when I use it as raw code 🤔
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