title: Nativescript-vue: 'admob createBanner error: Error: java.lang.NullPointerException
body: <p>i'm using the <strong>nativescript-admob</strong> plugin with <strong>nativescript-vue</strong>. 
  when i run i get this error :</p>
  
  <p><strong>JS: 'admob createBanner error: Error: java.lang.NullPointerException: Attempt to invoke virtual method \'android.content.res.Resources android.content.Context.getResources()\' on a null object reference'</strong></p>
  
  <p>my code:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code> created(){
              return this.banner();
          },
  methods: {
              banner(){
                   admob.createBanner({
                      testing: true,
                      size: admob.AD_SIZE.SMART_BANNER, 
                      androidBannerId: "ca-app-pub-3940256099942544/6300978111", // add your own
                      margins: {
                          //top: 10
                          bottom: 50
                      },
                      keywords: ["keyword1", "keyword2"] // add keywords for ad targeting
                  }).then(
                      function() {
                          console.log("admob createBanner done");
                      },
                      function(error) {
                          console.log("admob createBanner error: " + error);
                      }
                  )
  },</code></pre>
  </div>
  </div>
  </p>