ChromeDevTools SetVariableValue: how change object property? array cell?

Question

How to change an object property using the ChromeDevTools?

I ran the following code on nodejs with debugger support:

function test() {
    var obj = {
        "my_prop": 1
    }
    return obj; // <- breakpoint here
}

while (true) {
    test();
}

Then, I connected with the ChromeDevTools client. Set breakpoint on line 5 (return obj) and received the "Debugger.paused" event, in which I am trying to change the "my_prop" property of the "obj" object using Debugger.setVariableValue like the following code:

var frame = e.CallFrames[0];

var eval = await session.SendAsync(new Debugger.EvaluateOnCallFrameCommand
{
    CallFrameId = frame.CallFrameId,
    ReturnByValue = false,
    Timeout = 10000,
    GeneratePreview = true,
    IncludeCommandLineAPI = true,
    Silent = true,
    ThrowOnSideEffect = true,
    Expression = "obj"
});

var objectId = eval.Result.Result.ObjectId;

var set = await session.SendAsync(new Debugger.SetVariableValueCommand
{
    CallFrameId = frame.CallFrameId,
    ScopeNumber = 0,
    VariableName = "my_prop",
    NewValue = new Runtime.CallArgument
    {
        ObjectId = objectId,
        Value = 900,
        UnserializableValue = "900"
    },

});

But I get the error '-32603: Internal error'

The local variable is changed successfully using this code

Can anyone tell me where my mistake is?

---

SOLVED

I missed an important comment: "Object-based scopes are not supported"

I managed to make the necessary assignment through the Debugger.evaluateOnCallFrame:

var eval = await session.SendAsync(new EvaluateOnCallFrameCommand
{
    CallFrameId = frame.CallFrameId,
    ReturnByValue = true,
    Timeout = 10000,
    GeneratePreview = true,
    IncludeCommandLineAPI = true,
    Silent = true,
    ThrowOnSideEffect = false, <- must be false
    Expression = "obj.my_prop=100"
});

before that, the selected property was true and I got an error when calling this function, so I decided that I should use Debugger.setVariableValue