Express GraphQLObjectType不是构造函数

我正试图遵循graphql教程，尽管我遵循了它并仔细检查了一遍，但我一直得到上面的错误，我不知道为什么

当机器人要求你输入更多的代码时，你真的不讨厌吗？这主要是因为我没有线索，我发布了我所有的代码

const express = require("express");
const expressGraphQL = require("express-graphql");
const graphql = require("graphql");
const {
  GraphQlSchema,
  GraphQlObjectType,
  GraphQLString,
  GraphQLList,
  GraphQLInt,
  GraphQLNonNull,
} = graphql;
const app = express();

const authors = [
  { id: 1, name: "J. K. Rowling" },
  { id: 2, name: "J. R. R. Tolkien" },
  { id: 3, name: "Brent Weeks" },
];

const books = [
  { id: 1, name: "Harry Potter and the Chamber of Secrets", authorId: 1 },
  { id: 2, name: "Harry Potter and the Prisoner of Azkaban", authorId: 1 },
  { id: 3, name: "Harry Potter and the Goblet of Fire", authorId: 1 },
  { id: 4, name: "The Fellowship of the Ring", authorId: 2 },
  { id: 5, name: "The Two Towers", authorId: 2 },
  { id: 6, name: "The Return of the King", authorId: 2 },
  { id: 7, name: "The Way of Shadows", authorId: 3 },
  { id: 8, name: "Beyond the Shadows", authorId: 3 },
];

const BookType = new GraphQlObjectType({
  name: "Book",
  description: "A Book written by an author",
  fields: () => ({
    id: { type: GraphQLNonNull(GraphQLInt) },
    name: { type: GraphQLNonNull(GraphQLString) },
    authorId: { type: GraphQLNonNull(GraphQLInt) },
  }),
});
const RouteQueryType = new GraphQlObjectType({
  name: "Query",
  description: "Root Query",
  fields: () => ({
    books: new GraphQLList(BookType),
    description: "List of Books",
    resolve: () => books,
  }),
});

const schema = new GraphQlSchema({
  query: RouteQueryType,
});

app.use(
  "/graphql",
  expressGraphQL({
    schema: schema,
    graphiql: true,
  })
);
app.listen(5000, () => console.log("server running"));

---

错误的大写字母

GraphQlObjectType

应为

GraphQlObjectType