Fixed: checking of values to prevent notices
Fixed: checking of values to prevent notices

CPIGroup/phpAmazonMWS,creacoon/amazon-mws-laravel,Peardian/phpAmazonMWS,VincentWon/mws,kibokosrl/phpAmazonMWS,HMAZonderland/phpAmazonMWS,lapchenkovbyu/amazon-mws-laravel