[Fix] Subscription issue with coupon

Author: dipaksarkar

src/Http/Controllers/Subscription/SubscriptionController.php

@@ -92,7 +92,7 @@ public function subscribe(Request $request)
         $subscription = null;
         $metadata = $request->input('metadata') ?? [];
         $upgrade = false;
-        $coupon = Coupon::findByCode($request->promotion_code);
+        $coupon = optional(Coupon::findByCode($request->promotion_code));
 
         if ($isSubscribed && $user->subscription()->stripe_price == $planID) {
             throw ValidationException::withMessages([