diff --git a/packages/backend/src/server/api/endpoints/messaging/messages/create.ts b/packages/backend/src/server/api/endpoints/messaging/messages/create.ts
index f0916b7607..edc13c6810 100644
--- a/packages/backend/src/server/api/endpoints/messaging/messages/create.ts
+++ b/packages/backend/src/server/api/endpoints/messaging/messages/create.ts
@@ -29,7 +29,8 @@ export const meta = {
 
 	res: {
 		type: 'object',
-		optional: false, nullable: false,
+		optional: false,
+		nullable: false,
 		ref: 'MessagingMessage',
 	},
 
@@ -53,7 +54,7 @@ export const meta = {
 		},
 
 		groupAccessDenied: {
-			message: 'You can not send messages to groups that you have not joined.',
+			message: 'You cannot send messages to groups that you have not joined.',
 			code: 'GROUP_ACCESS_DENIED',
 			id: 'd96b3cca-5ad1-438b-ad8b-02f931308fbd',
 		},
@@ -111,8 +112,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private messagingService: MessagingService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			let recipientUser: MiUser | undefined = undefined;
-			let recipientGroup: MiUserGroup | undefined = undefined;
+			let recipientUser: MiUser;
+			let recipientGroup: MiUserGroup;
 
 			if (ps.userId != null) {
 				// Myself
@@ -134,11 +135,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				if (block) {
 					throw new ApiError(meta.errors.youHaveBeenBlocked);
 				}
-			} else if (ps.groupId != null) {
+			} else if (ps.groupId !== undefined) {
 				// Fetch recipient (group)
-				recipientGroup = await this.userGroupsRepository.findOneBy({ id: ps.groupId! });
+				recipientGroup = await this.userGroupsRepository.findOneBy({ id: ps.groupId });
 
-				if (recipientGroup == null) {
+				if (!recipientGroup) {
 					throw new ApiError(meta.errors.noSuchGroup);
 				}
 
@@ -148,7 +149,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 					userGroupId: recipientGroup.id,
 				});
 
-				if (joining == null) {
+				if (!joining) {
 					throw new ApiError(meta.errors.groupAccessDenied);
 				}
 			}