feat(angular): Add documentation for Sentry's ErrorHandler (#11361)

The new page about the Angular SDK's error handler explains
- what the error handler does / why it's necessary
- a couple of options (omitted the old `reportDialog` options in favour of User Feedback)
- how to handle multiple error handlers

---------

Co-authored-by: Liza Mock <liza.mock@sentry.io>

docs/platforms/javascript/guides/angular/features/error-handler.mdx

@@ -0,0 +1,82 @@
+---
+title: Angular Error Handler
+description: "Learn about Sentry's Angular SDK Error Handler and how to configure it."
+---
+
+Angular often wraps errors in its own error classes, making it hard for Sentry to extract the important data correctly without a custom error handler, which is where Sentry's Angular SDK `ErrorHandler` can help. On this page, you'll learn how to customize the SDK's `ErrorHandler` to work for your use case.
+
+## Using the Sentry `ErrorHandler`
+
+To get started, register the Sentry `ErrorHandler` in your Angular application's providers. We recommend to do this in your main `app.config.ts` or `app.module.ts` file to ensure that the `ErrorHandler` is available everywhere in your application.
+
+```typescript {tabTitle:App Config} {filename:app.config.ts} {3,8-11}
+import { ApplicationConfig, ErrorHandler } from "@angular/core";
+
+import * as Sentry from "@sentry/angular";
+
+export const appConfig: ApplicationConfig = {
+  providers: [
+    // ...
+    {
+      provide: ErrorHandler,
+      useValue: Sentry.createErrorHandler(),
+    },
+  ],
+};
+export class AppModule {}
+```
+
+```typescript {tabTitle:NGModule Config} {filename:app.module.ts} {3,8-11}
+import { ErrorHandler, NgModule } from "@angular/core";
+
+import * as Sentry from "@sentry/angular";
+
+@NgModule({
+  // ...
+  providers: [
+    {
+      provide: ErrorHandler,
+      useValue: Sentry.createErrorHandler(),
+    },
+  ],
+})
+export class AppModule {}
+```
+
+### Options
+
+As an alternative, you can configure the behavior of the `ErrorHandler` by passing an object to the `createErrorHandler` function. The following options are available:
+
+#### `logErrors`
+
+_Type: `boolean` Default: `true`_
+
+Lets you log errors to the console. This is `true` by default to ensure consistency with Angular's default behavior.
+
+#### `extractor`
+
+_Type: `function` Default: `undefined`_
+
+Lets you extract the raw, incoming error object. The SDK uses its own extraction logic by default, but you can override it by providing your own function.
+
+## Multiple Error Handlers
+
+Angular doesn't let you provide multiple `ErrorHandler` instances in the same Angular application in `app.config.ts` or `app.module.ts`.
+Therefore, if you're using your own error handler or you want to add additional logic to Sentry's `ErrorHandler`, you have to extend Sentry's `ErrorHandler` like in the example below:
+
+```typescript
+import * as Sentry from "@sentry/angular";
+
+export class CustomErrorHandler extends Sentry.ErrorHandler {
+  constructor() {
+    // Pass options to Sentry's ErrorHandler here. For Example:
+    super({ logErrors: false });
+  }
+
+  handleError(error: any): void {
+    // Your custom error handling logic
+    // Call Sentry's error handler to capture errors:
+    super.handleError(error);
+  }
+}
+```

platform-includes/getting-started-config/javascript.angular.mdx

@@ -139,7 +139,7 @@ import * as Sentry from "@sentry/angular";
 export class AppModule {}
 ```
 
-The `Sentry.createErrorHandler` function initializes a Sentry-specific `ErrorHandler` that automatically sends errors caught by Angular to Sentry. You can also customize the behavior by setting a couple of handler [options](https://github.com/getsentry/sentry-javascript/blob/master/packages/angular/src/errorhandler.ts).
+The `Sentry.createErrorHandler` function initializes a Sentry-specific `ErrorHandler` that automatically sends errors caught by Angular to Sentry. Learn how to further configure Sentry's `ErrorHandler` behavior [here](./features/error-handler).
 
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