Update dialoghelper.rst

Author: jdecoster

components/console/helpers/dialoghelper.rst

@@ -156,9 +156,10 @@ You can also ask and validate a hidden response::
     $dialog = $this->getHelperSet()->get('dialog');
 
     $validator = function ($value) {
-        if (trim($value) == '') {
+        if ('' === trim($value)) {
             throw new \Exception('The password can not be empty');
         }
+        
         return $value;
     };