keep focus on modal if no tabbable elements are within it

Author: everdimension

lib/helpers/scopeTab.js

@@ -2,7 +2,10 @@ var findTabbable = require('../helpers/tabbable');
 
 module.exports = function(node, event) {
   var tabbable = findTabbable(node);
-  if (!tabbable.length) return;
+  if (!tabbable.length) {
+      event.preventDefault();
+      return;
+  }
   var finalTabbable = tabbable[event.shiftKey ? 0 : tabbable.length - 1];
   var leavingFinalTabbable = (
     finalTabbable === document.activeElement ||