docs(angular): add type assertion for your first app code snippet (#2910

)

Was getting an error: "Type 'string | undefined' is not assignable to type 'string'." Adding an exclamation point at the end of line 111 solves it.

docs/angular/your-first-app/2-taking-photos.md

@@ -108,7 +108,7 @@ Over in the `addNewToGallery` function, add the newly captured photo to the begi
 
   this.photos.unshift({
     filepath: "soon...",
-    webviewPath: capturedPhoto.webPath
+    webviewPath: capturedPhoto.webPath!
   });
 }
 ```