🔑 Add key to avoid react error (#2577)

Author: rowanc1

.changeset/mighty-tires-double.md

@@ -0,0 +1,5 @@
+---
+'myst-common': patch
+---
+
+Add a key, results in a react error

packages/myst-common/src/extractParts.spec.ts

@@ -1,8 +1,17 @@
 import { describe, expect, it } from 'vitest';
-import { extractImplicitPart, extractPart } from './extractParts';
+import { extractImplicitPart as extractImplicitPartOriginal, extractPart } from './extractParts';
 import type { GenericParent } from '../dist';
 import { copyNode } from './utils';
 
+/** Remove keys for testing purposes from the parent nodes */
+function extractImplicitPart(...args: Parameters<typeof extractImplicitPartOriginal>) {
+  const part = extractImplicitPartOriginal(...args);
+  part?.children?.forEach((child) => {
+    delete child.key;
+  });
+  return part;
+}
+
 describe('extractPart', () => {
   it('no part returns undefined', async () => {
     expect(
@@ -597,6 +606,36 @@ describe('extractImplicitPart', () => {
       ],
     });
   });
+  it('original extractImplicitPart adds keys to the children', async () => {
+    const tree: GenericParent = {
+      type: 'root',
+      children: [
+        {
+          type: 'block',
+          children: [
+            {
+              type: 'heading',
+              children: [{ type: 'text', value: 'abstract' }],
+            },
+            {
+              type: 'paragraph',
+              children: [{ type: 'text', value: 'two' }],
+            },
+          ],
+        },
+        {
+          type: 'heading',
+          children: [{ type: 'text', value: 'abstract' }],
+        },
+        {
+          type: 'paragraph',
+          children: [{ type: 'text', value: 'four' }],
+        },
+      ],
+    };
+    const hasKeys = extractImplicitPartOriginal(tree, 'abstract');
+    expect(hasKeys?.children?.every((child) => child.key)).toBe(true);
+  });
   it('part headings with no content remain', async () => {
     const tree: GenericParent = {
       type: 'root',

packages/myst-common/src/extractParts.ts

@@ -2,7 +2,7 @@ import type { Block } from 'myst-spec-ext';
 import type { FrontmatterParts, GenericNode, GenericParent } from './types.js';
 import { remove } from 'unist-util-remove';
 import { selectAll } from 'unist-util-select';
-import { copyNode, toText } from './utils.js';
+import { copyNode, createId, toText } from './utils.js';
 import { FRONTMATTER_ALIASES } from 'myst-frontmatter';
 
 function coercePart(part?: string | string[]): string[] {
@@ -76,7 +76,7 @@ function createPartBlock(
     removePartData?: boolean;
   },
 ) {
-  const block: GenericParent = { type: 'block', children };
+  const block: GenericParent = { type: 'block', key: createId(), children };
   if (!opts?.removePartData) {
     block.data ??= {};
     block.data.part = part;