make redis client conditional

backend/src/services/RedisService.ts

@@ -1,3 +1,12 @@
 import { Redis } from "ioredis"
 
-export const redisClient = new Redis(process.env.REDIS_URL as string);
+let redisClient: Redis | null;
+
+if (process.env.REDIS_URL) {
+  redisClient = new Redis(process.env.REDIS_URL as string);
+} else {
+  console.warn("Redis URL not set, skipping Redis initialization.");
+  redisClient = null
+}
+
+export { redisClient }