toUndefinableFromErrUnwrap E if input is Err(E). Otherwise, return undefined. function toUndefinableFromErr<E>(input: Result<unknown, E>): Undefinable<E>;§toUndefinableFromErr<E>(input: Result<unknown, E>): Undefinable<E>[src]§Type Parameters§E[src]§Parameters§input: Result<unknown, E>[src]§Return Type§Undefinable<E>[src]