add enterprise guard

Author: adhami3310

reflex/app.py

@@ -529,6 +529,19 @@ def _setup_state(self) -> None:
 
         # Set up the Socket.IO AsyncServer.
         if not self.sio:
+            if (
+                config.transport == "polling"
+                and (tier := prerequisites.get_user_tier()) != "enterprise"
+            ):
+                console.error(
+                    "The 'polling' transport is only available for Enterprise users. "
+                    + (
+                        "Please upgrade your plan to use this feature."
+                        if tier != "anonymous"
+                        else "Please log in with `reflex login` to use this feature."
+                    )
+                )
+                raise SystemExit(1)
             self.sio = AsyncServer(
                 async_mode="asgi",
                 cors_allowed_origins=(