Add error callback (#27)

Author: wilson-ascenda

README.md

@@ -89,6 +89,7 @@ These options are well documented in the [Cloudflare Docs](https://developers.cl
 ### Events
 
 - `resolved(response: string)`. Occurs when the CAPTCHA resolution value changed.
+- `errored(errorCode: string)`. Occurs when the CAPTCHA widget returned an [error code](https://developers.cloudflare.com/turnstile/troubleshooting/client-side-errors/#error-codes).
 
 ### Example
 

projects/ngx-turnstile-demo/src/app/examples/event-binding/event-binding-example.component.ts

@@ -10,6 +10,7 @@ import { NgxTurnstileModule } from 'ngx-turnstile';
         [siteKey]="siteKey"
         theme="light"
         (resolved)="onResolved($event)"
+        (errored)="onErrored($event)"
       ></ngx-turnstile>
     </ng-container>
   `,
@@ -19,6 +20,10 @@ export class EventBindingExampleComponent {
   siteKey = '1x00000000000000000000AA';
 
   onResolved(response: string | null) {
-    console.log(response);
+    console.log('onResolved', response);
+  }
+
+  onErrored(errorCode: string | null) {
+    console.log('onErrored', errorCode);
   }
 }

projects/ngx-turnstile/src/lib/interfaces/turnstile-options.ts

@@ -3,7 +3,7 @@ export interface TurnstileOptions {
   action?: string;
   cData?: string;
   callback?: (token: string) => void;
-  'error-callback'?: () => void;
+  'error-callback'?: (errorCode: string) => boolean;
   'expired-callback'?: () => void;
   theme?: 'light' | 'dark' | 'auto';
   tabindex?: number;

projects/ngx-turnstile/src/lib/ngx-turnstile.component.ts

@@ -45,6 +45,7 @@ export class NgxTurnstileComponent implements AfterViewInit, OnDestroy {
   @Input() appearance?: 'always' | 'execute' | 'interaction-only' = 'always';
 
   @Output() resolved = new EventEmitter<string | null>();
+  @Output() errored = new EventEmitter<string | null>();
 
   private widgetId!: string;
 
@@ -72,6 +73,11 @@ export class NgxTurnstileComponent implements AfterViewInit, OnDestroy {
       callback: (token: string) => {
         this.zone.run(() => this.resolved.emit(token));
       },
+      'error-callback': (errorCode: string): boolean => {
+        this.zone.run(() => this.errored.emit(errorCode));
+        // Returning false causes Turnstile to log error code as a console warning.
+        return false;
+      },
       'expired-callback': () => {
         this.zone.run(() => this.reset());
       },