fix(pubsub): surface TLS config errors instead of silently degrading

resolveRedisTlsOptions (via getRedisConnectionDefaults) throws if
REDIS_TLS_SERVERNAME is missing for an IP-based rediss:// URL. Calling
it inside the constructor let createPubSubChannel's try/catch swallow
the error and fall back to in-process EventEmitter — silent
cross-replica pub/sub breakage in prod. Resolve defaults before the
try so config errors propagate; only catch genuine runtime construction
failures.

Author: TheodoreSpeaks

apps/sim/lib/events/pubsub.ts

@@ -32,10 +32,11 @@ class RedisPubSubChannel<T> implements PubSubChannel<T> {
 
   constructor(
     redisUrl: string,
+    connectionDefaults: ReturnType<typeof getRedisConnectionDefaults>,
     private config: PubSubChannelConfig
   ) {
     const commonOpts = {
-      ...getRedisConnectionDefaults(redisUrl),
+      ...connectionDefaults,
       maxRetriesPerRequest: null,
       retryStrategy: (times: number) => {
         if (times > 10) return 30000
@@ -138,16 +139,18 @@ class LocalPubSubChannel<T> implements PubSubChannel<T> {
 
 export function createPubSubChannel<T>(config: PubSubChannelConfig): PubSubChannel<T> {
   const redisUrl = env.REDIS_URL
-
-  if (redisUrl) {
-    try {
-      logger.info(`${config.label}: Using Redis`)
-      return new RedisPubSubChannel<T>(redisUrl, config)
-    } catch (err) {
-      logger.error(`Failed to create Redis ${config.label}, falling back to local:`, err)
-      return new LocalPubSubChannel<T>(config)
-    }
+  if (!redisUrl) return new LocalPubSubChannel<T>(config)
+
+  // Resolve config-derived defaults outside the try so a missing
+  // REDIS_TLS_SERVERNAME (config error) surfaces instead of silently degrading
+  // to the in-process EventEmitter — that would break cross-replica pub/sub.
+  const connectionDefaults = getRedisConnectionDefaults(redisUrl)
+
+  try {
+    logger.info(`${config.label}: Using Redis`)
+    return new RedisPubSubChannel<T>(redisUrl, connectionDefaults, config)
+  } catch (err) {
+    logger.error(`Failed to create Redis ${config.label}, falling back to local:`, err)
+    return new LocalPubSubChannel<T>(config)
   }
-
-  return new LocalPubSubChannel<T>(config)
 }