fix(spatial-navigation): refocus available also to the close button of the error modal (#8819)

## Description
This PR will make the refocus available not only to the buttons of the
error modal but also to the close button of the error modal on the event
of 'aftermodalfill'.

## Specific Changes proposed
Allow the spatial-navigation to refocus the error modal when error modal
appears.

## Requirements Checklist
- [x] Feature implemented / Bug fixed
- [ ] If necessary, more likely in a feature request than a bug fix
- [ ] Change has been verified in an actual browser (Chrome, Firefox,
IE)
  - [ ] Unit Tests updated or fixed
  - [ ] Docs/guides updated
- [ ] Example created ([starter template on
JSBin](https://codepen.io/gkatsev/pen/GwZegv?editors=1000#0))
- [ ] Has no DOM changes which impact accessiblilty or trigger warnings
(e.g. Chrome issues tab)
  - [ ] Has no changes to JSDoc which cause `npm run docs:api` to error
- [ ] Reviewed by Two Core Contributors

Author: CarlosVillasenor

src/js/spatial-navigation.js

@@ -62,9 +62,20 @@ class SpatialNavigation extends EventTarget {
     this.player_.errorDisplay.on('aftermodalfill', () => {
       this.updateFocusableComponents();
 
-      // Focus the buttons of the modal
-      if (this.focusableComponents.length > 1) {
-        this.focusableComponents[1].focus();
+      if (this.focusableComponents.length) {
+        // The modal has focusable components:
+
+        if (this.focusableComponents.length > 1) {
+          // The modal has close button + some additional buttons.
+          // Focusing first additional button:
+
+          this.focusableComponents[1].focus();
+        } else {
+          // The modal has only close button,
+          // Focusing it:
+
+          this.focusableComponents[0].focus();
+        }
       }
     });
   }