Fixed: TypeError on Keyup in Firefox for MovieIndex and Details

frontend/src/Movie/Details/MovieDetails.js

@@ -178,7 +178,7 @@ class MovieDetails extends Component {
   }
 
   onKeyUp = (event) => {
-    if (event.path.length === 4) {
+    if (event.composedPath && event.composedPath().length === 4) {
       if (event.keyCode === keyCodes.LEFT_ARROW) {
         this.props.onGoToMovie(this.props.previousMovie.titleSlug);
       }

frontend/src/Movie/Index/MovieIndex.js

@@ -246,7 +246,7 @@ class MovieIndex extends Component {
 
   onKeyUp = (event) => {
     const jumpBarItems = this.state.jumpBarItems.order;
-    if (event.path.length === 4) {
+    if (event.composedPath && event.composedPath().length === 4) {
       if (event.keyCode === keyCodes.HOME && event.ctrlKey) {
         this.setState({ jumpToCharacter: jumpBarItems[0] });
       }