apply the rest of fixes for snake flute, prevent players from seeing the npc perm error on join

TShockAPI/TSPlayer.cs

@@ -111,6 +111,11 @@ namespace TShockAPI
 			return found;
 		}
 
+		/// <summary>
+		/// Used in preventing players from seeing the npc spawnrate permission error on join.
+		/// </summary>
+		internal bool HasReceivedNPCPermissionError { get; set; }
+
 		/// <summary>
 		/// The amount of tiles that the player has killed in the last second.
 		/// </summary>