message: Fix Kotlin compilation error
diff: @@ -257,7 +257,7 @@ private fun createRenderable(
  // Find a material in the supplied material map, otherwise we fall back to
  // the default material named "DefaultMaterial"
  val material = materials[definedMaterials[parts[i].materialID.toInt()]]
  - material.let {
  + material?.let {
  builder.material(i, material)
  } ?: builder.material(i, materials["DefaultMaterial"]!!)
  }
  