1+++ 2title = "`static void narrow_error_check(Impl &&) noexcept`" 3description = "Observer policy performing hard UB if no error is present. Constexpr, never throws." 4categories = ["observer-policies"] 5weight = 410 6+++ 7 8Observer policy performing hard UB if no error is present, by calling {{% api "static void _ub(Impl &&)" %}}. Constexpr where possible. 9 10*Requires*: Always available. 11 12*Complexity*: Constant time. 13 14*Guarantees*: Never throws an exception. 15