message: don't assume config
diff: @@ -27,7 +27,7 @@ class FixedDistributor {
  this.sizer = sizer;
  this.item = item;
  this.beforeOffset = sizer.getItemOffset(this.item);
  - this.onResized = config.onResized;
  + this.onResized = config && config.onResized;
  }
  resize(offset) {
  