UnhandledRejectionListener
typealias UnhandledRejectionListener = (reason: Any?, @R|kotlin/ParameterName|(name = String(promise)) ERROR CLASS: Symbol not found for Promise<kotlin/Any?>) -> Unit(source)
Most of the time the unhandledRejection will be an Error, but this should not be relied upon as anything can be thrown/rejected, it is therefore unsafe to assume that the value is an Error.