expectErr

function Result.expectErr(result: Result<T, E>, message: string): E

Unwraps the Err value from the result. If the result is an Ok, throws a ResultError with the given message.

Example

data-first

Result.expectErr(err("fail"), "Expected an error");
// "fail"

Result.expectErr(ok(5), "Expected an error");
// throws ResultError("Expected an error")

data-last

pipe(err("fail"), Result.expectErr("Expected an error"));
// "fail"