const error_type &&assume_error() const && noexcept
Narrow contract const rvalue reference observer of the stored error. NoValuePolicy::narrow_error_check() is first invoked, then the reference to the error is returned. As a valid default constructed error is always present, no undefined behaviour occurs unless NoValuePolicy::narrow_error_check() does that.
Note that if error_type is void, only a const overload returning void is present.
Requires: Always available.
Complexity: Depends on NoValuePolicy::narrow_error_check().
Guarantees: An exception is never thrown.



