2.1.103 [W3C-HTML51] Section Unhandled promise rejections

V0421: The PromiseRejectionEvent interface is not supported

The specification states: Unhandled promise rejections
     In addition to synchronous runtime script errors, scripts may experience asynchronous 
     promise rejections, tracked via the unhandledrejection and rejectionhandled events. The HostPromiseRejectionTracker implementation
     ECMAScript contains an implementation-defined HostPromiseRejectionTracker(promise, 
     operation) abstract operation. User agents must use the following implementation: 
     [ECMA-262] The PromiseRejectionEvent interface
     [Constructor(DOMString type, PromiseRejectionEventInit eventInitDict), 
     interface PromiseRejectionEvent : Event {
         readonly attribute Promise<any> promise;
         readonly attribute any reason;

EdgeHTML Mode

The PromiseRejectionEvent interface is not supported.