Update index.js

index.js

@@ -294,7 +294,7 @@ app.post("/api/v2/key/upgrade-key", authenticateApiKey, apiLimiter, async (req,
     }
 
     if (!existingUser) {
-      return res.status(404).json({ error: "API key not found" });
+      return res.status(404).json({ error: "API key expired and deleted. Generate a new key." });
     }
 
     const expirationDate = new Date();