What is the cause of the function error?

The following is the error statement is ‘if(Masu4 = Hu1):’ of line80
“This function parameter expects a value of type tuple(comparable,comparable), but this argument is an incompatible value of type tuple(creative_prop,creative_prop).”

What is this mysterious error?
I have never defined it with the COMPARABLE type and yet I am being asked to do so.

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }
using { /UnrealEngine.com/Temporary/Diagnostics }
using { /UnrealEngine.com/Temporary/SpatialMath }

animal_shogi := class(creative_device):
@editable
Hu1 : creative_prop = creative_prop{}
@editable
Hu2 : creative_prop = creative_prop{}
@editable
Kaku1 : creative_prop = creative_prop{}
@editable
Kaku2 : creative_prop = creative_prop{}
@editable
Hisya1 : creative_prop = creative_prop{}
@editable
Hisya2 : creative_prop = creative_prop{}
@editable
Ou1 : creative_prop = creative_prop{}
@editable
Ou2 : creative_prop = creative_prop{}

@editable 
PropManipulator0 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator1 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator2 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator3 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator4 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator5 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator6 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator7 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator8 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator9 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator10 : prop_manipulator_device = prop_manipulator_device{}
@editable 
PropManipulator11 : prop_manipulator_device = prop_manipulator_device{}

var Masu : []tuple(int, creative_prop, prop_manipulator_device) = array{}


OnBegin<override>()<suspends>:void=
    set Masu = 
        array{(0, Kaku1, PropManipulator0), 
        (1, Ou1, PropManipulator1), 
        (2, Hisya1, PropManipulator2), 
        (3, creative_prop{}, PropManipulator3), 
        (4, Hu1, PropManipulator4), 
        (5, creative_prop{}, PropManipulator5), 
        (6, creative_prop{}, PropManipulator6), 
        (7, Hu2, PropManipulator7),
        (8, creative_prop{}, PropManipulator8),
        (9, Hisya2, PropManipulator9), 
        (10, Ou2, PropManipulator10), 
        (11, Kaku2, PropManipulator11)}
    PropManipulator4Damaged()

PropManipulator4Damaged():void=
    PropManipulator4.DamagedEvent.Subscribe(OnDamagedEvent4)

OnDamagedEvent4(Agent : agent):void=
    IsKomaValid()

IsKomaValid():void=
    if(Masu[4](1).IsValid[]):
        if(Masu[4](1) = Hu1):

To compare equivalency of two classes they need to add the <unique> class specifier. You can read about that on the Specifiers and Attributes docs page.

class_type := class():

class_type_unique := class<unique>():

Test():void=
        
    # Can be compared
    if(ClassA := class_type_unique{}, ClassB := class_type_unique{}, ClassA = ClassB):

    # Errors, class is not unique
    if(ClassA := class_type{}, ClassB := class_type{}, ClassA = ClassB):

It looks like the creative_prop is not unique and so you can’t compare it in the way you have tried.