How to color polygones with null values in Apache Superset chart type deck.gl

Question

I have a deck.gl chart in an Apache Superset dashboard. It is colored by a value. Some of the entries don't have a value and they are colored dark grey by default. I'd like to change that color.

I'm using Superset version 2.1.0.

I tried to use the Javascript Data Interceptor

function modifyData(dataArray) {
    // Iterate over the data array
    for (let i = 0; i < dataArray.length; i++) {
        // Check if the value associated with each element is null
        if (dataArray[i].value === null) {
            // Set the color to yellow for polygons with null values
            dataArray[i].color = 'yellow';
        }
    }
    // Return the modified data array
    return dataArray;
}

but this did not change the color of the null-value polygones.