Added code coverage blocks

src/OAuth2/Util/SecureKey.php

@@ -13,7 +13,9 @@ class SecureKey
 
         // We want to stop execution if the key fails because, well, that is bad.
         if ($bytes === false || $strong === false) {
+            // @codeCoverageIgnoreStart
             throw new \Exception('Error Generating Key');
+            // @codeCoverageIgnoreEnd
         }
 
         return substr(str_replace(array('/', '+', '='), '', base64_encode($bytes)), 0, $len);