fix(backend): correct invalid schema format specifying only `required` for `anyOf` (#16089)

* fix(backend): correct invalid schema format specifying only `required` for `anyOf`

* refactor(backend): make types derived from `allOf` or `anyOf` more strong

12 files changed, 318 insertions, 184 deletions

diff --git a/packages/backend/src/server/api/endpoints/admin/drive/show-file.ts b/packages/backend/src/server/api/endpoints/admin/drive/show-file.ts
index a7136d8c8c..b84a5c73f9 100644
--- a/packages/backend/src/server/api/endpoints/admin/drive/show-file.ts
+++ b/packages/backend/src/server/api/endpoints/admin/drive/show-file.ts
@@ -162,14 +162,21 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		fileId: { type: 'string', format: 'misskey:id' },
-		url: { type: 'string' },
-	},
 	anyOf: [
-		{ required: ['fileId'] },
-		{ required: ['url'] },
+		{
+			type: 'object',
+			properties: {
+				fileId: { type: 'string', format: 'misskey:id' },
+			},
+			required: ['fileId'],
+		},
+		{
+			type: 'object',
+			properties: {
+				url: { type: 'string' },
+			},
+			required: ['url'],
+		},
 	],
 } as const;
 
@@ -186,15 +193,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private idService: IdService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const file = ps.fileId ? await this.driveFilesRepository.findOneBy({ id: ps.fileId }) : await this.driveFilesRepository.findOne({
-				where: [{
-					url: ps.url,
-				}, {
-					thumbnailUrl: ps.url,
-				}, {
-					webpublicUrl: ps.url,
-				}],
-			});
+			const file = await this.driveFilesRepository.findOneBy(
+				'fileId' in ps
+					? { id: ps.fileId }
+					: [{ url: ps.url }, { thumbnailUrl: ps.url }, { webpublicUrl: ps.url }],
+			);
 
 			if (file == null) {
 				throw new ApiError(meta.errors.noSuchFile);
diff --git a/packages/backend/src/server/api/endpoints/admin/emoji/update.ts b/packages/backend/src/server/api/endpoints/admin/emoji/update.ts
index 6834a6d213..7bde10af46 100644
--- a/packages/backend/src/server/api/endpoints/admin/emoji/update.ts
+++ b/packages/backend/src/server/api/endpoints/admin/emoji/update.ts
@@ -37,29 +37,45 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		id: { type: 'string', format: 'misskey:id' },
-		name: { type: 'string', pattern: '^[a-zA-Z0-9_]+$' },
-		fileId: { type: 'string', format: 'misskey:id' },
-		category: {
-			type: 'string',
-			nullable: true,
-			description: 'Use `null` to reset the category.',
+	allOf: [
+		{
+			anyOf: [
+				{
+					type: 'object',
+					properties: {
+						id: { type: 'string', format: 'misskey:id' },
+					},
+					required: ['id'],
+				},
+				{
+					type: 'object',
+					properties: {
+						name: { type: 'string', pattern: '^[a-zA-Z0-9_]+$' },
+					},
+					required: ['name'],
+				},
+			],
+		},
+		{
+			type: 'object',
+			properties: {
+				fileId: { type: 'string', format: 'misskey:id' },
+				category: {
+					type: 'string',
+					nullable: true,
+					description: 'Use `null` to reset the category.',
+				},
+				aliases: { type: 'array', items: {
+					type: 'string',
+				} },
+				license: { type: 'string', nullable: true },
+				isSensitive: { type: 'boolean' },
+				localOnly: { type: 'boolean' },
+				roleIdsThatCanBeUsedThisEmojiAsReaction: { type: 'array', items: {
+					type: 'string',
+				} },
+			},
 		},
-		aliases: { type: 'array', items: {
-			type: 'string',
-		} },
-		license: { type: 'string', nullable: true },
-		isSensitive: { type: 'boolean' },
-		localOnly: { type: 'boolean' },
-		roleIdsThatCanBeUsedThisEmojiAsReaction: { type: 'array', items: {
-			type: 'string',
-		} },
-	},
-	anyOf: [
-		{ required: ['id'] },
-		{ required: ['name'] },
 	],
 } as const;
 
@@ -78,10 +94,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				if (driveFile == null) throw new ApiError(meta.errors.noSuchFile);
 			}
 
-			// JSON schemeのanyOfの型変換がうまくいっていないらしい
-			const required = { id: ps.id, name: ps.name } as
-				| { id: MiEmoji['id']; name?: string }
-				| { id?: MiEmoji['id']; name: string };
+			const required = 'id' in ps
+				? { id: ps.id, name: 'name' in ps ? ps.name as string : undefined }
+				: { name: ps.name };
 
 			const error = await this.customEmojiService.update({
 				...required,
diff --git a/packages/backend/src/server/api/endpoints/drive/files/show.ts b/packages/backend/src/server/api/endpoints/drive/files/show.ts
index e8f4539d61..9a2e2c73e8 100644
--- a/packages/backend/src/server/api/endpoints/drive/files/show.ts
+++ b/packages/backend/src/server/api/endpoints/drive/files/show.ts
@@ -43,14 +43,21 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		fileId: { type: 'string', format: 'misskey:id' },
-		url: { type: 'string' },
-	},
 	anyOf: [
-		{ required: ['fileId'] },
-		{ required: ['url'] },
+		{
+			type: 'object',
+			properties: {
+				fileId: { type: 'string', format: 'misskey:id' },
+			},
+			required: ['fileId'],
+		},
+		{
+			type: 'object',
+			properties: {
+				url: { type: 'string' },
+			},
+			required: ['url'],
+		},
 	],
 } as const;
 
@@ -64,21 +71,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private roleService: RoleService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			let file: MiDriveFile | null = null;
-
-			if (ps.fileId) {
-				file = await this.driveFilesRepository.findOneBy({ id: ps.fileId });
-			} else if (ps.url) {
-				file = await this.driveFilesRepository.findOne({
-					where: [{
-						url: ps.url,
-					}, {
-						webpublicUrl: ps.url,
-					}, {
-						thumbnailUrl: ps.url,
-					}],
-				});
-			}
+			const file = await this.driveFilesRepository.findOneBy(
+				'fileId' in ps
+					? { id: ps.fileId }
+					: [{ url: ps.url }, { webpublicUrl: ps.url }, { thumbnailUrl: ps.url }],
+			);
 
 			if (file == null) {
 				throw new ApiError(meta.errors.noSuchFile);
diff --git a/packages/backend/src/server/api/endpoints/i/revoke-token.ts b/packages/backend/src/server/api/endpoints/i/revoke-token.ts
index c05ee93c6f..08f5e3a7a1 100644
--- a/packages/backend/src/server/api/endpoints/i/revoke-token.ts
+++ b/packages/backend/src/server/api/endpoints/i/revoke-token.ts
@@ -15,14 +15,21 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		tokenId: { type: 'string', format: 'misskey:id' },
-		token: { type: 'string', nullable: true },
-	},
 	anyOf: [
-		{ required: ['tokenId'] },
-		{ required: ['token'] },
+		{
+			type: 'object',
+			properties: {
+				tokenId: { type: 'string', format: 'misskey:id' },
+			},
+			required: ['tokenId'],
+		},
+		{
+			type: 'object',
+			properties: {
+				token: { type: 'string', nullable: true },
+			},
+			required: ['token'],
+		},
 	],
 } as const;
 
@@ -33,7 +40,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private accessTokensRepository: AccessTokensRepository,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			if (ps.tokenId) {
+			if ('tokenId' in ps) {
 				const tokenExist = await this.accessTokensRepository.exists({ where: { id: ps.tokenId } });
 
 				if (tokenExist) {
diff --git a/packages/backend/src/server/api/endpoints/notes/search-by-tag.ts b/packages/backend/src/server/api/endpoints/notes/search-by-tag.ts
index d0781bd8dd..3e41b33d03 100644
--- a/packages/backend/src/server/api/endpoints/notes/search-by-tag.ts
+++ b/packages/backend/src/server/api/endpoints/notes/search-by-tag.ts
@@ -28,38 +28,53 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		reply: { type: 'boolean', nullable: true, default: null },
-		renote: { type: 'boolean', nullable: true, default: null },
-		withFiles: {
-			type: 'boolean',
-			default: false,
-			description: 'Only show notes that have attached files.',
+	allOf: [
+		{
+			anyOf: [
+				{
+					type: 'object',
+					properties: {
+						tag: { type: 'string', minLength: 1 },
+					},
+					required: ['tag'],
+				},
+				{
+					type: 'object',
+					properties: {
+						query: {
+							type: 'array',
+							description: 'The outer arrays are chained with OR, the inner arrays are chained with AND.',
+							items: {
+								type: 'array',
+								items: {
+									type: 'string',
+									minLength: 1,
+								},
+								minItems: 1,
+							},
+							minItems: 1,
+						},
+					},
+					required: ['query'],
+				},
+			],
 		},
-		poll: { type: 'boolean', nullable: true, default: null },
-		sinceId: { type: 'string', format: 'misskey:id' },
-		untilId: { type: 'string', format: 'misskey:id' },
-		limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
-
-		tag: { type: 'string', minLength: 1 },
-		query: {
-			type: 'array',
-			description: 'The outer arrays are chained with OR, the inner arrays are chained with AND.',
-			items: {
-				type: 'array',
-				items: {
-					type: 'string',
-					minLength: 1,
+		{
+			type: 'object',
+			properties: {
+				reply: { type: 'boolean', nullable: true, default: null },
+				renote: { type: 'boolean', nullable: true, default: null },
+				withFiles: {
+					type: 'boolean',
+					default: false,
+					description: 'Only show notes that have attached files.',
 				},
-				minItems: 1,
+				poll: { type: 'boolean', nullable: true, default: null },
+				sinceId: { type: 'string', format: 'misskey:id' },
+				untilId: { type: 'string', format: 'misskey:id' },
+				limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
 			},
-			minItems: 1,
 		},
-	},
-	anyOf: [
-		{ required: ['tag'] },
-		{ required: ['query'] },
 	],
 } as const;
 
@@ -87,12 +102,12 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			if (me) this.queryService.generateBlockedUserQueryForNotes(query, me);
 
 			try {
-				if (ps.tag) {
+				if ('tag' in ps) {
 					if (!safeForSql(normalizeForSearch(ps.tag))) throw new Error('Injection');
 					query.andWhere(':tag <@ note.tags', { tag: [normalizeForSearch(ps.tag)] });
 				} else {
 					query.andWhere(new Brackets(qb => {
-						for (const tags of ps.query!) {
+						for (const tags of ps.query) {
 							qb.orWhere(new Brackets(qb => {
 								for (const tag of tags) {
 									if (!safeForSql(normalizeForSearch(tag))) throw new Error('Injection');
diff --git a/packages/backend/src/server/api/endpoints/pages/show.ts b/packages/backend/src/server/api/endpoints/pages/show.ts
index e08b832a3f..8427bab2d5 100644
--- a/packages/backend/src/server/api/endpoints/pages/show.ts
+++ b/packages/backend/src/server/api/endpoints/pages/show.ts
@@ -33,15 +33,22 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		pageId: { type: 'string', format: 'misskey:id' },
-		name: { type: 'string' },
-		username: { type: 'string' },
-	},
 	anyOf: [
-		{ required: ['pageId'] },
-		{ required: ['name', 'username'] },
+		{
+			type: 'object',
+			properties: {
+				pageId: { type: 'string', format: 'misskey:id' },
+			},
+			required: ['pageId'],
+		},
+		{
+			type: 'object',
+			properties: {
+				name: { type: 'string' },
+				username: { type: 'string' },
+			},
+			required: ['name', 'username'],
+		},
 	],
 } as const;
 
@@ -59,9 +66,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		super(meta, paramDef, async (ps, me) => {
 			let page: MiPage | null = null;
 
-			if (ps.pageId) {
+			if ('pageId' in ps) {
 				page = await this.pagesRepository.findOneBy({ id: ps.pageId });
-			} else if (ps.name && ps.username) {
+			} else {
 				const author = await this.usersRepository.findOneBy({
 					host: IsNull(),
 					usernameLower: ps.username.toLowerCase(),
diff --git a/packages/backend/src/server/api/endpoints/users/followers.ts b/packages/backend/src/server/api/endpoints/users/followers.ts
index a8b4319a61..bb8d4c49e9 100644
--- a/packages/backend/src/server/api/endpoints/users/followers.ts
+++ b/packages/backend/src/server/api/endpoints/users/followers.ts
@@ -47,23 +47,38 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		sinceId: { type: 'string', format: 'misskey:id' },
-		untilId: { type: 'string', format: 'misskey:id' },
-		limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
-
-		userId: { type: 'string', format: 'misskey:id' },
-		username: { type: 'string' },
-		host: {
-			type: 'string',
-			nullable: true,
-			description: 'The local host is represented with `null`.',
+	allOf: [
+		{
+			anyOf: [
+				{
+					type: 'object',
+					properties: {
+						userId: { type: 'string', format: 'misskey:id' },
+					},
+					required: ['userId'],
+				},
+				{
+					type: 'object',
+					properties: {
+						username: { type: 'string' },
+						host: {
+							type: 'string',
+							nullable: true,
+							description: 'The local host is represented with `null`.',
+						},
+					},
+					required: ['username', 'host'],
+				},
+			],
+		},
+		{
+			type: 'object',
+			properties: {
+				sinceId: { type: 'string', format: 'misskey:id' },
+				untilId: { type: 'string', format: 'misskey:id' },
+				limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
+			},
 		},
-	},
-	anyOf: [
-		{ required: ['userId'] },
-		{ required: ['username', 'host'] },
 	],
 } as const;
 
@@ -85,9 +100,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private roleService: RoleService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const user = await this.usersRepository.findOneBy(ps.userId != null
+			const user = await this.usersRepository.findOneBy('userId' in ps
 				? { id: ps.userId }
-				: { usernameLower: ps.username!.toLowerCase(), host: this.utilityService.toPunyNullable(ps.host) ?? IsNull() });
+				: { usernameLower: ps.username.toLowerCase(), host: this.utilityService.toPunyNullable(ps.host) ?? IsNull() });
 
 			if (user == null) {
 				throw new ApiError(meta.errors.noSuchUser);
diff --git a/packages/backend/src/server/api/endpoints/users/following.ts b/packages/backend/src/server/api/endpoints/users/following.ts
index feda5bb353..1fc87151b2 100644
--- a/packages/backend/src/server/api/endpoints/users/following.ts
+++ b/packages/backend/src/server/api/endpoints/users/following.ts
@@ -54,25 +54,39 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		sinceId: { type: 'string', format: 'misskey:id' },
-		untilId: { type: 'string', format: 'misskey:id' },
-		limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
-
-		userId: { type: 'string', format: 'misskey:id' },
-		username: { type: 'string' },
-		host: {
-			type: 'string',
-			nullable: true,
-			description: 'The local host is represented with `null`.',
+	allOf: [
+		{
+			anyOf: [
+				{
+					type: 'object',
+					properties: {
+						userId: { type: 'string', format: 'misskey:id' },
+					},
+					required: ['userId'],
+				},
+				{
+					type: 'object',
+					properties: {
+						username: { type: 'string' },
+						host: {
+							type: 'string',
+							nullable: true,
+							description: 'The local host is represented with `null`.',
+						},
+					},
+					required: ['username', 'host'],
+				},
+			],
+		},
+		{
+			type: 'object',
+			properties: {
+				sinceId: { type: 'string', format: 'misskey:id' },
+				untilId: { type: 'string', format: 'misskey:id' },
+				limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
+				birthday: { ...birthdaySchema, nullable: true },
+			},
 		},
-
-		birthday: { ...birthdaySchema, nullable: true },
-	},
-	anyOf: [
-		{ required: ['userId'] },
-		{ required: ['username', 'host'] },
 	],
 } as const;
 
@@ -94,9 +108,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private roleService: RoleService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			const user = await this.usersRepository.findOneBy(ps.userId != null
+			const user = await this.usersRepository.findOneBy('userId' in ps
 				? { id: ps.userId }
-				: { usernameLower: ps.username!.toLowerCase(), host: this.utilityService.toPunyNullable(ps.host) ?? IsNull() });
+				: { usernameLower: ps.username.toLowerCase(), host: this.utilityService.toPunyNullable(ps.host) ?? IsNull() });
 
 			if (user == null) {
 				throw new ApiError(meta.errors.noSuchUser);
diff --git a/packages/backend/src/server/api/endpoints/users/relation.ts b/packages/backend/src/server/api/endpoints/users/relation.ts
index 1d75437b81..f146095cf1 100644
--- a/packages/backend/src/server/api/endpoints/users/relation.ts
+++ b/packages/backend/src/server/api/endpoints/users/relation.ts
@@ -114,7 +114,7 @@ export const paramDef = {
 	type: 'object',
 	properties: {
 		userId: {
-			anyOf: [
+			oneOf: [
 				{ type: 'string', format: 'misskey:id' },
 				{
 					type: 'array',
diff --git a/packages/backend/src/server/api/endpoints/users/search-by-username-and-host.ts b/packages/backend/src/server/api/endpoints/users/search-by-username-and-host.ts
index 134f1a8e87..d1d6354d53 100644
--- a/packages/backend/src/server/api/endpoints/users/search-by-username-and-host.ts
+++ b/packages/backend/src/server/api/endpoints/users/search-by-username-and-host.ts
@@ -26,17 +26,32 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
-		detail: { type: 'boolean', default: true },
-
-		username: { type: 'string', nullable: true },
-		host: { type: 'string', nullable: true },
-	},
-	anyOf: [
-		{ required: ['username'] },
-		{ required: ['host'] },
+	allOf: [
+		{
+			anyOf: [
+				{
+					type: 'object',
+					properties: {
+						username: { type: 'string', nullable: true },
+					},
+					required: ['username'],
+				},
+				{
+					type: 'object',
+					properties: {
+						host: { type: 'string', nullable: true },
+					},
+					required: ['host'],
+				},
+			],
+		},
+		{
+			type: 'object',
+			properties: {
+				limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
+				detail: { type: 'boolean', default: true },
+			},
+		},
 	],
 } as const;
 
@@ -47,8 +62,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 	) {
 		super(meta, paramDef, (ps, me) => {
 			return this.userSearchService.searchByUsernameAndHost({
-				username: ps.username,
-				host: ps.host,
+				username: 'username' in ps ? ps.username : undefined,
+				host: 'host' in ps ? ps.host : undefined,
 			}, {
 				limit: ps.limit,
 				detail: ps.detail,
diff --git a/packages/backend/src/server/api/endpoints/users/show.test.ts b/packages/backend/src/server/api/endpoints/users/show.test.ts
new file mode 100644
index 0000000000..068ffd8bc9
--- /dev/null
+++ b/packages/backend/src/server/api/endpoints/users/show.test.ts
@@ -0,0 +1,23 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+process.env.NODE_ENV = 'test';
+
+import { getValidator } from '../../../../../test/prelude/get-api-validator.js';
+import { paramDef } from './show.js';
+
+const VALID = true;
+const INVALID = false;
+
+describe('api:users/show', () => {
+	describe('validation', () => {
+		const v = getValidator(paramDef);
+
+		test('Reject empty', () => expect(v({})).toBe(INVALID));
+		test('Reject host only', () => expect(v({ host: 'misskey.test' })).toBe(INVALID));
+		test('Accept userId only', () => expect(v({ userId: '1' })).toBe(VALID));
+		test('Accept username and host', () => expect(v({ username: 'alice', host: 'misskey.test' })).toBe(VALID));
+	});
+});
diff --git a/packages/backend/src/server/api/endpoints/users/show.ts b/packages/backend/src/server/api/endpoints/users/show.ts
index 431869d47f..d57db42e6d 100644
--- a/packages/backend/src/server/api/endpoints/users/show.ts
+++ b/packages/backend/src/server/api/endpoints/users/show.ts
@@ -59,23 +59,44 @@ export const meta = {
 } as const;
 
 export const paramDef = {
-	type: 'object',
-	properties: {
-		userId: { type: 'string', format: 'misskey:id' },
-		userIds: { type: 'array', uniqueItems: true, items: {
-			type: 'string', format: 'misskey:id',
-		} },
-		username: { type: 'string' },
-		host: {
-			type: 'string',
-			nullable: true,
-			description: 'The local host is represented with `null`.',
+	allOf: [
+		{
+			anyOf: [
+				{
+					type: 'object',
+					properties: {
+						userId: { type: 'string', format: 'misskey:id' },
+					},
+					required: ['userId'],
+				},
+				{
+					type: 'object',
+					properties: {
+						userIds: { type: 'array', uniqueItems: true, items: {
+							type: 'string', format: 'misskey:id',
+						} },
+					},
+					required: ['userIds'],
+				},
+				{
+					type: 'object',
+					properties: {
+						username: { type: 'string' },
+					},
+					required: ['username'],
+				},
+			],
+		},
+		{
+			type: 'object',
+			properties: {
+				host: {
+					type: 'string',
+					nullable: true,
+					description: 'The local host is represented with `null`.',
+				},
+			},
 		},
-	},
-	anyOf: [
-		{ required: ['userId'] },
-		{ required: ['userIds'] },
-		{ required: ['username'] },
 	],
 } as const;
 
@@ -102,9 +123,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			let user;
 
 			const isModerator = await this.roleService.isModerator(me);
-			ps.username = ps.username?.trim();
+			if ('username' in ps) {
+				ps.username = ps.username.trim();
+			}
 
-			if (ps.userIds) {
+			if ('userIds' in ps) {
 				if (ps.userIds.length === 0) {
 					return [];
 				}
@@ -129,7 +152,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				return _users.map(u => _userMap.get(u.id)!);
 			} else {
 				// Lookup user
-				if (typeof ps.host === 'string' && typeof ps.username === 'string') {
+				if (typeof ps.host === 'string' && 'username' in ps) {
 					if (this.serverSettings.ugcVisibilityForVisitor === 'local' && me == null) {
 						throw new ApiError(meta.errors.noSuchUser);
 					}
@@ -139,7 +162,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 						throw new ApiError(meta.errors.failedToResolveRemoteUser);
 					});
 				} else {
-					const q: FindOptionsWhere<MiUser> = ps.userId != null
+					const q: FindOptionsWhere<MiUser> = 'userId' in ps
 						? { id: ps.userId }
 						: { usernameLower: ps.username!.toLowerCase(), host: IsNull() };