message: fix undefined error
diff: @@ -47,6 +47,9 @@ export function MaterialCounts() {
  )}
  {matgroup.map((h) => {
  const items = materials[h];
  + if (!items) {
  + return null;
  + }
  const amount = items.reduce((total, i) => total + i.amount, 0);
  const item = items[0];
  const materialName = item.name;
  