fix(getExtendedNodes): parentNode is null in first iteration

Author: rwieruch

src/common/util/tree/getExtendedNodes.ts

@@ -1,6 +1,6 @@
 import { TableNode } from '@table-library/react-table-library/types/table';
 
-export const getExtendedNodes = (nodes: TableNode[], parentNode: TableNode): TableNode[] => {
+export const getExtendedNodes = (nodes: TableNode[], parentNode: TableNode | null): TableNode[] => {
   const extendedNodes = nodes.map((node) => ({
     ...node,
     ancestors: parentNode ? parentNode.ancestors.concat(node) : [node],