fix(backend): clips/updateのdescriptionで空文字を許容するように (#15429)

* fix(backend): clips/updateのdescriptionで空文字を許容するように

* Update Changelog

* fix: createの際も空文字を許容するように

* fix test

* fix test

---------

Co-authored-by: syuilo <4439005+syuilo@users.noreply.github.com>

packages/backend/test/e2e/clips.ts

@@ -182,7 +182,6 @@ describe('クリップ', () => {
 		{ label: 'nameがnull', parameters: { name: null } },
 		{ label: 'nameが最大長+1', parameters: { name: 'x'.repeat(101) } },
 		{ label: 'isPublicがboolじゃない', parameters: { isPublic: 'true' } },
-		{ label: 'descriptionがゼロ長', parameters: { description: '' } },
 		{ label: 'descriptionが最大長+1', parameters: { description: 'a'.repeat(2049) } },
 	];
 	test.each(createClipDenyPattern)('の作成は$labelならできない', async ({ parameters }) => failedApiCall({
@@ -199,6 +198,23 @@ describe('クリップ', () => {
 		id: '3d81ceae-475f-4600-b2a8-2bc116157532',
 	}));
 
+	test('の作成はdescriptionが空文字ならnullになる', async () => {
+		const clip = await successfulApiCall({
+			endpoint: 'clips/create',
+			parameters: {
+				...defaultCreate(),
+				description: '',
+			},
+			user: alice,
+		});
+
+		assert.deepStrictEqual(clip, {
+			...clip,
+			...defaultCreate(),
+			description: null,
+		});
+	});
+
 	test('の更新ができる', async () => {
 		const res = await update({
 			clipId: (await create()).id,
@@ -249,6 +265,24 @@ describe('クリップ', () => {
 		...assertion,
 	}));
 
+	test('の更新はdescriptionが空文字ならnullになる', async () => {
+		const clip = await successfulApiCall({
+			endpoint: 'clips/update',
+			parameters: {
+				clipId: (await create()).id,
+				name: 'updated',
+				description: '',
+			},
+			user: alice,
+		});
+
+		assert.deepStrictEqual(clip, {
+			...clip,
+			name: 'updated',
+			description: null,
+		});
+	});
+
 	test('の削除ができる', async () => {
 		await deleteClip({
 			clipId: (await create()).id,