expectErr method
Returns the held value of this Result
if it is Err. Throws a ResultError
with the given message
and held Ok value if this Result
is Ok.
See also:
Rust: Result::expect_err()
Implementation
E expectErr(String message) => switch (this) {
Ok(:T v) => throw ResultError('$message: $v', isExpected: true),
Err(:E e) => e
};