code: function makeRenderLayerTask(layer) {
      return function renderLayer(next) {
        var stackupLayer = makeBaseStackupLayer(layer)
  
        if (stackupLayer.converter) return next(null, stackupLayer)
  
        var converter = gerberToSvg(
          stackupLayer.gerber,
          stackupLayer.options,
          function handleLayerDone(error) {
            if (error) return next(error)
            stackupLayer.converter = converter
            next(null, stackupLayer)
          }
        )
      }
    }
docs: map an pcb-stackup input layer into a function that will call a callback once a pcb-stackup-core input layer is ready