Hotfix: change the way of checking array size and condition check

Author: coderimus

app/code/Magento/Backend/Model/Widget/Grid/Parser.php

@@ -30,8 +30,8 @@ public function parseExpression($expression)
         $expression = trim($expression);
         foreach ($this->_operations as $operation) {
             $splittedExpr = preg_split('/\\' . $operation . '/', $expression, -1, PREG_SPLIT_DELIM_CAPTURE);
-            if (!empty($splittedExpr)) {
-                $count = count($splittedExpr);
+            $count = count($splittedExpr);
+            if ($count > 1) {
                 for ($i = 0; $i < $count; $i++) {
                     $stack = array_merge($stack, $this->parseExpression($splittedExpr[$i]));
                     if ($i > 0) {