feat: OnDiscardedError typings and event (#6777)

* feat: OnDiscardedError typings and event

* remove ios and android from DiscardedErrorEventData

apps/app/ui-tests-app/app.ts

@@ -81,6 +81,13 @@ application.on(application.uncaughtErrorEvent, function(args: application.Unhand
     console.log("### stack: " + args.error.stack);
 });
 
+application.on(application.discardedErrorEvent, function(args: application.DiscardedErrorEventData) {
+    console.log("### [Discarded] NativeScriptError: " + args.error);
+    console.log("### [Discarded] nativeException: " + (<any>args.error).nativeException);
+    console.log("### [Discarded] stackTrace: " + (<any>args.error).stackTrace);
+    console.log("### [Discarded] stack: " + args.error.stack);
+});
+
 application.setCssFileName("ui-tests-app/app.css");
 
 application.start({ moduleName: "ui-tests-app/main-page" });

tests/app/app/app.ts

@@ -90,6 +90,12 @@ application.on(application.uncaughtErrorEvent, function (args: application.Unhan
     console.log((<any>args.error).stackTrace || (<any>args.error).stack);
 });
 
+application.on(application.discardedErrorEvent, function (args: application.DiscardedErrorEventData) {
+    console.log("[Discarded] NativeScriptError: " + args.error);
+    console.log((<any>args.error).nativeException || (<any>args.error).nativeError);
+    console.log((<any>args.error).stackTrace || (<any>args.error).stack);
+});
+
 // Android activity events
 if (application.android) {
     application.android.on(application.AndroidApplication.activityCreatedEvent, function (args: application.AndroidActivityBundleEventData) {

tns-core-modules/application/application-common.ts

@@ -38,10 +38,11 @@ import {
     getRootView,
     iOSApplication,
     LoadAppCSSEventData,
-    UnhandledErrorEventData
+    UnhandledErrorEventData,
+    DiscardedErrorEventData
 } from "./application";
 
-export { UnhandledErrorEventData, CssChangedEventData, LoadAppCSSEventData };
+export { UnhandledErrorEventData, DiscardedErrorEventData, CssChangedEventData, LoadAppCSSEventData };
 
 export const launchEvent = "launch";
 export const suspendEvent = "suspend";
@@ -50,6 +51,7 @@ export const resumeEvent = "resume";
 export const exitEvent = "exit";
 export const lowMemoryEvent = "lowMemory";
 export const uncaughtErrorEvent = "uncaughtError";
+export const discardedErrorEvent = "discardedError";
 export const orientationChangedEvent = "orientationChanged";
 
 let cssFile: string = "./app.css";
@@ -122,3 +124,7 @@ export function addCss(cssText: string): void {
 global.__onUncaughtError = function (error: NativeScriptError) {
     events.notify(<UnhandledErrorEventData>{ eventName: uncaughtErrorEvent, object: app, android: error, ios: error, error: error });
 }
+
+global.__onDiscardedError = function (error: NativeScriptError) {
+    events.notify(<DiscardedErrorEventData>{ eventName: discardedErrorEvent, object: app, error: error });
+}

tns-core-modules/application/application.d.ts

@@ -21,6 +21,11 @@ export var displayedEvent: string;
  */
 export var uncaughtErrorEvent: string;
 
+/**
+ * String value used when hooking to discardedError event.
+ */
+export var discardedErrorEvent: string;
+
 /**
  * String value used when hooking to suspend event.
  */
@@ -103,6 +108,13 @@ export interface UnhandledErrorEventData extends ApplicationEventData {
     error: NativeScriptError;
 }
 
+/**
+ * Event data containing information about discarded application errors.
+ */
+export interface DiscardedErrorEventData extends ApplicationEventData {
+    error: NativeScriptError;
+}
+
 /**
  * Event data containing information about application css change.
  */
@@ -262,6 +274,11 @@ export function on(event: "lowMemory", callback: (args: ApplicationEventData) =>
  */
 export function on(event: "uncaughtError", callback: (args: UnhandledErrorEventData) => void, thisArg?: any);
 
+/**
+ * This event is raised when an discarded error occurs while the application is running.
+ */
+export function on(event: "discardedError", callback: (args: DiscardedErrorEventData) => void, thisArg?: any);
+
 /**
  * This event is raised the orientation of the current device has changed.
  */

tns-core-modules/module.d.ts

@@ -54,6 +54,7 @@ declare namespace NodeJS {
         __onLiveSync: (context?: { type: string, module: string }) => void;
         __onLiveSyncCore: () => void;
         __onUncaughtError: (error: NativeScriptError) => void;
+        __onDiscardedError: (error: NativeScriptError) => void;
         TNS_WEBPACK?: boolean;
         __requireOverride?: (name: string, dir: string) => any;
     }