Merge pull request #2391 from mgralikowski/patch-1

[9.0] Fix issue with non-existing variables/attributes .

Author: yajra

src/CollectionDataTable.php

@@ -295,9 +295,9 @@ protected function getSorter(array $criteria)
                     $second = $b;
                 }
                 if ($this->config->isCaseInsensitive()) {
-                    $cmp = strnatcasecmp($first[$column], $second[$column]);
+                    $cmp = strnatcasecmp($first[$column] ?? null, $second[$column] ?? null);
                 } else {
-                    $cmp = strnatcmp($first[$column], $second[$column]);
+                    $cmp = strnatcmp($first[$column] ?? null, $second[$column] ?? null);
                 }
                 if ($cmp != 0) {
                     return $cmp;