some fix

src/ListJsonTable.php

@@ -29,7 +29,7 @@ class ListJsonTable extends JasonTable
 
     #[NoReturn] public function __construct(string $json)
     {
-        $this->beforePrintCell = false;
+        $this->beforePrintCell = [];
         $this->json = $json;
         $this->data = json_decode($this->json, true);
         $this->baseUrl = $this->data['meta']['baseUrl'] ?? '';
@@ -86,7 +86,7 @@ class ListJsonTable extends JasonTable
                 }
                 foreach ($row as $key => $cell) {
                     if ($this->issetColumn($key) and $this->is_fillable($key)) {
-                        if($this->beforePrintCell and $cell !== null) {
+                        if($this->beforePrintCell) {
                             $cell = $this->getCustomCell($key, $cell);
                         }
                         $this->html .= "<td>" . $cell . "</td>";