revert: undo unnecessary subscription null→undefined change

getHighestPrioritySubscription never throws (it catches internally
and returns null), so the catch block in preprocessExecution is dead
code. The null vs undefined distinction doesn't matter and the
coercions added unnecessary complexity.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/lib/execution/preprocessing.ts

@@ -265,7 +265,7 @@ export async function preprocessExecution(
   }
 
   // ========== STEP 4: Get Subscription ==========
-  let userSubscription: SubscriptionInfo | undefined
+  let userSubscription: SubscriptionInfo = null
   try {
     userSubscription = await getHighestPrioritySubscription(actorUserId)
   } catch (error) {
@@ -350,7 +350,7 @@ export async function preprocessExecution(
       const rateLimiter = new RateLimiter()
       rateLimitInfo = await rateLimiter.checkRateLimitWithSubscription(
         actorUserId,
-        userSubscription ?? null,
+        userSubscription,
         triggerType,
         false // not async
       )
@@ -419,7 +419,7 @@ export async function preprocessExecution(
     success: true,
     actorUserId,
     workflowRecord,
-    userSubscription: userSubscription ?? null,
+    userSubscription,
     rateLimitInfo,
     executionTimeout: {
       sync: getExecutionTimeout(plan, 'sync'),