Noissue - Check if driver exists before destroying it, wait for result

test/all.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 77 matching lines @@
     for (let file of glob.sync("./test/wrappers/*.js"))
     {
       // Reload the module(s) for every browser
       let modulePath = path.resolve(file);
       delete require.cache[require.resolve(modulePath)];
       require(modulePath);
     }
 
     after(function()
     {
-      this.driver.quit();
+      if (this.driver)
+        return this.driver.quit();
     });
   });
 }