[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:1665](https://github.com/evoluhq/evolu/blob/dd96d79f1dbe9a49fa12ce8e0aa7d3d0177795ca/packages/common/src/Task.ts#L1665)

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).