[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Task](https://evolu.dev/docs/api-reference/common/Task) › InferFiberErr

```ts
type InferFiberErr<TFiber> =
  TFiber extends Fiber<any, infer E, any> ? E : never;
```

Defined in: [packages/common/src/Task.ts:1666](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Task.ts#L1666)

Extracts the [Result](https://evolu.dev/docs/api-reference/common/Result/type-aliases/Result) error type from a [Fiber](https://evolu.dev/docs/api-reference/common/Task/interfaces/Fiber).