Why does 'Owner of Unit' return 16 here?

[Liquidj]

Can someone help me understand why I'm getting these errors in the console using this event? Why would I be getting a value of 16 for a player?

00:00:15.19 Trigger Error in 'lib1_gt_DetectSupplyBlock_Func': Could not get 'player' from parameter in 'PlayerGetPropertyInt' (value: 16)
00:00:15.19 Trigger Error in 'lib1_gt_DetectSupplyBlock_Func': Could not get 'player' from parameter in 'PlayerGetPropertyInt' (value: 16)
00:00:15.19 Trigger Error in 'lib1_gt_DetectSupplyBlock_Func': Could not get 'player' from parameter in 'PlayerGetPropertyInt' (value: 16)
00:00:15.19 Trigger Error in 'lib1_gt_DetectSupplyBlock_Func': Could not get 'player' from parameter in 'PlayerGetPropertyInt' (value: 16)

Detect Supply Block
    Events
        Unit - Any Unit training progress is Started
    Local Variables
        i_player = 0 <Integer>
        i_suppliesUsed = 0 <Integer>
    Conditions
    Actions
        Variable - Set i_player = (Owner of (Triggering progress unit))
        Variable - Set i_suppliesUsed = (Player i_player Supplies Used)
        General - If (Conditions) then do (Actions) else do (Actions)
            If
                And
                    Conditions
                        i_suppliesUsed >= (Player i_player Supplies Made)
                        i_suppliesUsed < ((Player i_player Supplies Limit) - 10)
            Then
                General - If (Conditions) then do (Actions) else do (Actions)
                    If
                        (Elapsed time of gi_arr_supplyBlockedTimers[(Owner of (Triggering progress unit))]) == 0.0
                    Then
                        ------- Timer is set to last longer than the 1 minute score check time.
                        Debug - Display ("Supply Blocked @ (" + (Combine ((Text(i_suppliesUsed)), "/", (Text((Player i_player Supplies Made))), ")"))) as debug output using Type 1, and Do display it in the game window
                        Timer - Start gi_arr_supplyBlockedTimers[i_player] as a One Shot timer that will expire in 61.0 Game Time seconds
                    Else
                        Debug - Display ("Supply Blocked @ (" + (Combine ((Text(i_suppliesUsed)), "/", (Text((Player i_player Supplies Made))), ")"))) as debug output using Type 1, and Do display it in the game window
                        Timer - Unpause gi_arr_supplyBlockedTimers[i_player]
            Else
                Debug - Display ("Supply Available @ (" + (Combine ((Text(i_suppliesUsed)), "/", (Text((Player i_player Supplies Made))), ")"))) as debug output using Type 1, and Do display it in the game window

 

[Liquidj]

I'm an idiot. For anyone else who stays up so late that they become stupid, this trigger's instructions clearly say to use (triggering player) to find the player that triggered the train.