useTexture hook can't be conditional

[portedison]

I have a conditional alphaMap, sometimes I have it, sometimes not, but I can't make the hook conditional, how do I 'unset' the aphaMap when the fabric is updated and doesn't have a value?

  const { scene, nodes, materials } = useGLTF(model.path as string);

  const lightMap = useTexture(model.light, (map) => {
    applyProps(map, {
      needsUpdate: true,
    });
  });
  const fabricMaps = useTexture(
    {
      alphaMap: fabric.texture_map.alpha_file,
      roughnessMap: fabric.texture_map.metallic_roughness_file,
      normalMap: fabric.texture_map.normal_file,
      map: fabric.texture_map.base_color_file,
    }, ....