Do not show page if exception's not from Mink

src/Behat/MinkExtension/Listener/FailureShowListener.php

@@ -7,6 +7,7 @@ use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Behat\Behat\Event\StepEvent;
 
 use Behat\Mink\Mink;
+use Behat\Mink\Exception\Exception as MinkException;
 
 /*
  * This file is part of the Behat\MinkExtension.
@@ -80,6 +81,10 @@ class FailureShowListener implements EventSubscriberInterface
             return;
         }
         
+        if (!$event->getException() instanceof MinkException) {
+            return;
+        }
+
         if (null === $this->parameters['show_cmd']) {
             throw new \RuntimeException('Set "show_cmd" parameter in behat.yml to be able to open page in browser (ex.: "show_cmd: open %s")');
         }