title: How to check for NULL when mapping nested JSON?
body: <p>I'm trying to map a nested JSON to the model object, the problem is when it returns null, it will break all the code, I want to check if null do something but not break the app.</p>
  
  <p><strong>THE JSON FILE:</strong> </p>
  
  <pre><code>[
      {
          "id": 53,
          "date": "2018-12-28T08:51:11",
          "title": {
              "rendered": "this is for featured"
          },
          "content": {
              "rendered": "\n&lt;p&gt;&lt;g class=\"gr_ gr_3 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling\" id=\"3\" data-gr-id=\"3\"&gt;sdafkj&lt;/g&gt; &lt;g class=\"gr_ gr_10 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace\" id=\"10\" data-gr-id=\"10\"&gt;kj&lt;/g&gt; &lt;g class=\"gr_ gr_16 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace\" id=\"16\" data-gr-id=\"16\"&gt;asd&lt;/g&gt; &lt;g class=\"gr_ gr_18 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling\" id=\"18\" data-gr-id=\"18\"&gt;kadjsfk&lt;/g&gt; kljadfklj sd&lt;/p&gt;\n",
              "protected": false
          },
          "excerpt": {
              "rendered": "&lt;p&gt;sdafkj kj asd kadjsfk kljadfklj sd&lt;/p&gt;\n",
              "protected": false
          },
          "author": 1,
          "featured_media": 54,
          "_links": {
              "self": [
                  {
                      "href": "https://client.kurd.app/wp-json/wp/v2/posts/53"
                  }
              ],
  
          },
          "_embedded": {
              "author": [
                  {
                      "id": 1,
                      "name": "hooshyar",
  
                  }
              ],
              "wp:featuredmedia": [
                  {
                      "id": 54,
  
                      "source_url": "https://client.kurd.app/wp-content/uploads/2018/12/icannotknow_22_12_2018_18_48_11_430.jpg",
                      }
                      ]
  }
  ]
  </code></pre>
  
  <p>CODE FOR MAPPING TO OBJECT:</p>
  
  <pre><code>  featuredMediaUrl = map ["_embedded"]["wp:featuredmedia"][0]["source_url"];
  </code></pre>
  
  <p>The method 'map' was called on null.
  Receiver: null [0] which sometimes returns null ;</p>