docs: fix http example to show actual message in console (#42773)

Previously, the error message in the console would print `[object Object]`
and not the actual error message. With this change, the error message is
printed in the console.

PR Close #42773

aio/content/examples/http/src/app/config/config.service.ts

@@ -79,8 +79,7 @@ export class ConfigService {
       // The backend returned an unsuccessful response code.
       // The response body may contain clues as to what went wrong.
       console.error(
-        `Backend returned code ${error.status}, ` +
-        `body was: ${error.error}`);
+        `Backend returned code ${error.status}, body was: `, error.error);
     }
     // Return an observable with a user-facing error message.
     return throwError(