can't save data in mongoose 7.2.2 with error Cannot read properties of undefined (reading 'options') at getEmbeddedDiscriminatorPath

I am working with mongoose (7.2.2) to save an object into mongodb. The schema is shown below

// database schema 
const schema = Schema({
"name":{type:String},
"description":{type:String},
"database":{ 
type:{type:String},
url:{ type:String },
db:{ type:String },
username:{ type:String },
password:{ type:String },
},
"schema":[ {type:Schema.Types.Mixed} ],
},{
timestamps: true, 
virtuals: true,
toJSON: {
transform: (docs, ret) => {
const obj = ret;
obj.id = obj._id;
delete obj.__v;
return obj;
}
}
});
mongoose.model('data_assets',dataAssetsSchema);
// save the data
const collection = mongoose.model('data_assets');
return await collection.create(data);
// data example
{
schema: [
{
name: 'name',
column: 'name',
role: 'dimension',
type: 'string'
},
{ name: 'latitude', column: 'latitude', role: 'measure', type: 'float' },
{
name: 'longtitude',
column: 'longtitude',
role: 'measure',
type: 'float'
}
],
name: 'china_train_station',
database: {
url: 'mongodb://localhost:27017',
username: '',
password: '',
db: 'test',
collection: 'station',
indexing: 'name'
}
}

I see nothing wrong with the code but saving the data gives me the error.

err TypeError: Cannot read properties of undefined (reading 'options')
at getEmbeddedDiscriminatorPath (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/helpers/document/getEmbeddedDiscriminatorPath.js:25:79)
at model.$set (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/document.js:1149:16)
at model.$set (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/document.js:1208:14)
at model.$set (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/document.js:1100:14)
at model.Document (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/document.js:165:12)
at model.Model (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/model.js:122:12)
at new model (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/model.js:4609:15)
at /Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/model.js:2853:16
at Array.map (<anonymous>)
at Function.create (/Users/Documents/code/data/server2/node_modules/_mongoose@7.2.2@mongoose/lib/model.js:2842:38)

Never encounter the problem before, I am very confused

"mongoose": "^7.2.1"

The database field of the seed data does not match the database field schema.

const dataAssetsSchema = Schema({
  name: String,
  database: {
    type: { type: String },
    url: { type: String },
    db: { type: String },
    username: { type: String },
    password: { type: String },
    collection: String,
    indexing: String,
  },
  schema: [{ type: Schema.Types.Mixed }],
})

// seed data
const data = {
  schema: [
    {
      name: 'name',
      column: 'name',
      role: 'dimension',
      type: 'string',
    },
  ],
  name: 'china_train_station',
  database: {
    type: 'NOSQL',
    url: 'mongodb://localhost:27017',
    username: '',
    password: '',
    db: 'test',
    collection: 'station',
    indexing: 'name',
  },
};