message: fix: Type converters threw on older TS versions
diff: @@ -77,6 +77,10 @@ export function loadConverters() {
  unionConverter,
  ]) {
  for (const key of actor.kind) {
  + if (key === undefined) {
  + // Might happen if running on an older TS version.
  + continue;
  + }
  assert(!converters.has(key));
  converters.set(key, actor);
  }
  