Fix captions.toggle() if there is no toggle button

src/js/captions.js

@@ -191,8 +191,10 @@ const captions = {
                 return;
             }
 
-            // Toggle state
+            // Toggle button if it's enabled
+            if (this.elements.buttons.captions) {
                 this.elements.buttons.captions.pressed = active;
+            }
 
             // Add class hook
             toggleClass(this.elements.container, activeClass, active);