Node.js 填充导致结果丢失的字段

我正在使用express和mongo在Node中制作一个应用程序。在尝试填充查询结果时，当我尝试填充特定字段时，结果会丢失，请您指出此处的错误

project.ts文件

import mongoose, { Schema, Document } from 'mongoose';
import { IUser } from './user';
import { IFiles } from './file'
import { ICategory } from './category'
import { ITags } from './tags'

export interface featured_image {
    data: Buffer;
    contentType: String;
}
export interface IProject extends Document {
  ...
  user: IUser['_id'];
  files: Array< IFiles['_id'] >;
  tags: Array< ITags['_id'] >;
  category: ICategory['_id'];
  .....
}


const ProjectSchema: Schema = new Schema({
        ....
        user: {
          type: Schema.Types.ObjectId,
          ref: "User"
        },
        files: [{
          type: Schema.Types.ObjectId,
          ref: "File"
        }],
        category :{
          type: Schema.Types.ObjectId,
          ref: "Category"
        },
        tags : [{
            type: Schema.Types.ObjectId,
            ref: "Tags"
          }]
        .........

    },
    { timestamps: true }
);


export default mongoose.model<IProject>('Project', ProjectSchema);

它返回：

{
    "error": "Project not found"
}

如果我只是删除

.populate（'tags'）

，我会得到相同项目的实际结果

注意：当我测试这个时，标签数组是空的

import mongoose, { Schema, Document } from 'mongoose';
import { ICategory } from './category';
export interface ITags extends Document {
  name: string;
  type: string;
  count:number;
  category:ICategory['_id'];
}

const TagsSchema: Schema = new Schema({
        name: {
          type: String,
          unique:true,
          lowercase:true
        },
        type:{
          type:string, //project category | profile | project tag
        },
        count: Number,
        category: {
          type: Schema.Types.ObjectId,
          ref: "Category"
        }
    },
    { timestamps: true }
);


export default mongoose.model<ITags>('Tags', TagsSchema);

{
    "error": "Project not found"
}