fix: handle case if librarian is only one

Author: sideseal

Diff for: src/rotation/rotations.service.ts

@@ -69,15 +69,22 @@ export class RotationsService {
 
     if (tomorrowLibrarian.length === 0) {
       return;
-    }
+    } else if (tomorrowLibrarian.length === 1) {
+      const tomorrowLibrarianOne = tomorrowLibrarian[0].user;
 
-    const tomorrowLibrarianOne = tomorrowLibrarian[0].user;
-    const tomorrowLibrarianTwo = tomorrowLibrarian[1].user;
+      const message = `[알림] 내일은 ${tomorrowLibrarianOne.nickname}님이 사서입니다!`;
 
-    const message = `[알림] 내일은 ${tomorrowLibrarianOne.nickname}님과 ${tomorrowLibrarianTwo.nickname}님이 사서입니다!`;
+      await this.slackService.sendDirectMessage(tomorrowLibrarianOne.slackMemberId, message);
+      return;
+    } else {
+      const tomorrowLibrarianOne = tomorrowLibrarian[0].user;
+      const tomorrowLibrarianTwo = tomorrowLibrarian[1].user;
 
-    await this.slackService.sendDirectMessage(tomorrowLibrarianOne.slackMemberId, message);
-    await this.slackService.sendDirectMessage(tomorrowLibrarianTwo.slackMemberId, message);
+      const message = `[알림] 내일은 ${tomorrowLibrarianOne.nickname}님과 ${tomorrowLibrarianTwo.nickname}님이 사서입니다!`;
+
+      await this.slackService.sendDirectMessage(tomorrowLibrarianOne.slackMemberId, message);
+      await this.slackService.sendDirectMessage(tomorrowLibrarianTwo.slackMemberId, message);
+    }
   }
 
   /*

Diff for: src/slack/slack.service.ts

@@ -9,7 +9,7 @@ export class SlackService {
 
   async sendDirectMessage(slackId: string, message: string): Promise<void> {
     if (slackId.length === 0 || slackId === undefined || slackId === null) {
-      this.logger.warn('Slack ID is not defined');
+      this.logger.warn('Slack ID is not defined or empty.');
       return;
     }