fix: 🐛 use correct symbol for lists ending with null

Author: streamich

src/__tests__/printTree.spec.ts

@@ -108,3 +108,22 @@ Array
         └─ item 2`,
   );
 });
+
+test('last child is angle, when end of list is "null"', () => {
+  // prettier-ignore
+  const str = 'Array' + printTree('', [
+    (tab) => '[0]:' + printTree(tab + ' ', [
+      (tab) => 'item 1',
+      null,
+    ]),
+    null,
+    null,
+  ]);
+
+  expect('\n' + str).toBe(
+    `
+Array
+└─ [0]:
+    └─ item 1`,
+  );
+});

src/printTree.ts

@@ -2,9 +2,9 @@ import type {PrintChild} from './types';
 
 export const printTree = (tab = '', children: (PrintChild | null)[]): string => {
   let str = '';
-  const length = children.length;
-  const last = length - 1;
-  for (let i = 0; i < length; i++) {
+  let last = children.length - 1;
+  for (; last >= 0; last--) if (children[last]) break;
+  for (let i = 0; i <= last; i++) {
     const fn = children[i];
     if (!fn) continue;
     const isLast = i === last;