handleError method
Handle any error, potentially recovering from it, by mapping it to an Either value.
Applies the given function f
if this is a Left and return the result wrapped in a Right,
otherwise returns this if this is a Right.
Implementation
Either<L, R> handleError(R Function(L value) f) => _foldInternal(
ifLeft: (v) => f(v).right(),
ifRight: (v) => v.right(),
);