Need to fix index load issues

SVSim.EmulatedEntrypoint/Services/SteamSessionService.cs

@@ -19,6 +19,14 @@ public class SteamSessionService : IDisposable
     /// <returns>whether the ticket is valid for the given steamid</returns>
     public bool IsTicketValidForUser(string ticket, ulong steamId)
     {
+        if (string.IsNullOrEmpty(ticket))
+        {
+            // Caller already shouldn't pass null/empty here, but a misshaped request body
+            // (e.g. wrong casing) used to NRE on the ConcurrentDictionary lookup below.
+            // Fail cleanly so the auth pipeline returns 401 instead of crashing the request.
+            return false;
+        }
+
         if (_validatedSessionTickets.TryGetValue(ticket, out ulong storedSteamId))
         {
             return storedSteamId == steamId;