Undefinded index existing in Input\Renderer\Validator\File.php

[gfobe]

Poorly I can not reproduce where it was come from, but my error log says to me

2016-03-14T16:45:02+00:00 ERR (3): Notice: Undefined index: existing in \vendor\webguys\easytemplate\app\code\community\Webguys\Easytemplate\Model\Input\Renderer\Validator\File.php on line 35

Magento 1.9.2.4 @ Firefox 44 Win7/64 & PHP5.6.11