message: fix: Ensure null is never put into visited types memory
diff: @@ -273,15 +273,15 @@ function getFlowTypeWithResolvedTypes(path: NodePath): FlowTypeDescriptor {
  }
  }
  + if (!type) {
  + type = { name: 'unknown' };
  + }
  +
  if (isTypeAlias) {
  // mark the type as unvisited so that further calls can resolve the type again
  visitedTypes[path.parentPath.node.id.name] = type;
  }
  - if (!type) {
  - type = { name: 'unknown' };
  - }
  -
  return type;
  }
  