You need to check that the clientid is valid in CheckPlayerLoadout() to prevent spamming this:
Code:
L 03/31/2010 - 03:53:29: [SM] Native "GetPlayerWeaponSlot" reported: Entity index 0 is not a valid client
L 03/31/2010 - 03:53:29: [SM] Displaying call stack trace for plugin "superlogs-tf2.smx":
L 03/31/2010 - 03:53:29: [SM] [0] Line 983, superlogs-tf2.sp::CheckPlayerLoadout()