MongoNotConnectedError（'运行操作前必须连接客户端'）；如何处理这个问题？

这个问题？"/>

MongoNotConnectedError（'运行操作前必须连接客户端'）；如何处理这个问题？

每次运行代码时都会收到以下错误消息：

G:\Web Development\Projects\simple-crud-server\node_modules\mongodb\lib\operations\execute_operation.js:23
            throw new error_1.MongoNotConnectedError('Client must be connected before running operations');
                  ^

MongoNotConnectedError: Client must be connected before running operations
    at executeOperationAsync (G:\Web Development\Projects\simple-crud-server\node_modules\mongodb\lib\operations\execute_operation.js:23:19)
    at G:\Web Development\Projects\simple-crud-server\node_modules\mongodb\lib\operations\execute_operation.js:12:45
    at maybeCallback (G:\Web Development\Projects\simple-crud-server\node_modules\mongodb\lib\utils.js:278:21)
    at executeOperation (G:\Web Development\Projects\simple-crud-server\node_modules\mongodb\lib\operations\execute_operation.js:12:38)
    at Collection.insertOne (G:\Web Development\Projects\simple-crud-server\node_modules\mongodb\lib\collection.js:145:57)       
    at G:\Web Development\Projects\simple-crud-server\index.js:38:43
    at Layer.handle [as handle_request] (G:\Web Development\Projects\simple-crud-server\node_modules\express\lib\router\layer.js:95:5)
    at next (G:\Web Development\Projects\simple-crud-server\node_modules\express\lib\router\route.js:144:13)
    at Route.dispatch (G:\Web Development\Projects\simple-crud-server\node_modules\express\lib\router\route.js:114:3)
    at Layer.handle [as handle_request] (G:\Web Development\Projects\simple-crud-server\node_modules\express\lib\router\layer.js:95:5) {
  [Symbol(errorLabels)]: Set(0) {}
}
[nodemon] app crashed - waiting for file changes before starting...

我正在尝试从客户端在数据库中设置数据。但是每次我得到上面的错误。 作为参考（如果有帮助），这是我创建并运行的种子文件：

我该如何解决这个错误？