Merge pull request #868 from friday/null-no-controls

Fix string "null" being appended after the video if controls argument is empty.

src/js/controls.js

@@ -1233,7 +1233,7 @@ const controls = {
         // Inject controls HTML
         if (utils.is.element(container)) {
             target.appendChild(container);
-        } else {
+        } else if (container) {
             target.insertAdjacentHTML('beforeend', container);
         }