[orx-gui] `gui.add(linearGradient)` fails when using OKLab colors

[hamoid]

Operating System

Linux

OPENRNDR version

from git

ORX version

from git

Java version (if applicable)

No response

Describe the bug

↑ class org.openrndr.extra.color.spaces.ColorOKLABa cannot be cast to class org.openrndr.color.ColorRGBa (org.openrndr.extra.color.spaces.ColorOKLABa and org.openrndr.color.ColorRGBa are in unnamed module of loader 'app') (ClassCastException) 

Steps to reproduce the bug

import org.openrndr.application
import org.openrndr.color.ColorRGBa
import org.openrndr.extra.color.spaces.toOKLABa
import org.openrndr.extra.gui.GUI
import org.openrndr.extra.shadestyles.LinearGradientOKLab

fun main() = application {
    program {
        val g = LinearGradientOKLab(
            ColorRGBa.RED.toOKLABa(),
            ColorRGBa.GREEN.toOKLABa()
        )

        extend(GUI()) { add(g, "linear gradient") }
        extend {}
    }
}

[hamoid]

Issue still present on 0b87c96