message: milestoneDef
  handles classified milestones
diff: @@ -285,7 +285,7 @@ export class Progress extends React.Component<Props, State> {
  // Sort them alphabetically by name
  return _.sortBy(filteredMilestones, (milestone) => {
  const milestoneDef = defs.Milestone.get(milestone.milestoneHash);
  - if (milestoneDef.displayProperties) {
  + if (milestoneDef && milestoneDef.displayProperties) {
  return milestoneDef.displayProperties.name;
  } else if (milestone.availableQuests) {
  const questDef = milestoneDef.quests[milestone.availableQuests[0].questItemHash];
  