angular: Elvis Operator fail with object that Arrary?

Hi, I was creating an example that recive a json from public Api, the json’s structure is:

{
    "success": {
        "total": 1
    },
    "contents": {
        "quotes": [
            {
                "quote": "Never waste your time trying to explain who you are to people who are committed to misunderstanding you.",
                "length": "104",
                "author": "Dream Hampton",
                "tags": [
                    "inspire",
                    "misunderstanding",
                    "tso-life",
                    "tso-management",
                    "wasting-time"
                ],
                "category": "inspire",
                "date": "2016-01-31",
                "title": "Inspiring Quote of the day",
                "background": "https://theysaidso.com/img/bgs/man_on_the_mountain.jpg",
                "id": "OVmnzpHewxSTCw3AXDgnpweF"
            }
        ]
    }
}

But in my template when I try to use elvis operator It fails. I got the error

EXCEPTION: TypeError: Cannot read property ‘0’ of null in [{{quote?.contents?.quotes[0]?.quote}} in App@4:20]

import {Component, OnInit, Injectable} from 'angular2/core';
import {Http, HTTP_PROVIDERS, URLSearchParams} from 'angular2/http';
import 'rxjs/add/operator/map';

@Component({
  selector: 'app',
  template: `<ul>
                <li (click)='myAlert()'> Helow World</li>
             </ul>
             <div>
              <spam>{{quote?.contents?.quotes[0]?.quote}}</spam>
             </div>`,
  providers: [HTTP_PROVIDERS]
})

export class App {
  public quote: Object;
  public  logError: string;

  constructor(private http: Http){
    this.quote = {};
  }

  myAlert(){
      this.http.get("http://quotes.rest/qod.json").map(res => { return res.json()})
        .subscribe(
          data => this.quote = data,
          err => this.logError(err),
          () => console.log('Random Quote Complete')
      );

  }
}

It failed because I’m trying to use an Elvis operator with an object that has an array. It works perfect with nested objects without array. I’m missing something??