find queries with embeddables fail if eager relation loaded with with JOINED strategy

[oznakn]

Describe the bug

em.find queries fail if an entity that includes both an embeddable and eager one-to-many relationship used.

Stack trace

TypeError: Cannot read properties of undefined (reading '0')
    at SqliteDriver.mapPropToFieldNames (.../node_modules/@mikro-orm/knex/AbstractSqlDriver.js:496:97)
    at .../node_modules/@mikro-orm/knex/AbstractSqlDriver.js:473:44
    at Array.forEach (<anonymous>)
    at SqliteDriver.getFieldsForJoinedLoad (.../node_modules/@mikro-orm/knex/AbstractSqlDriver.js:473:8)
    at SqliteDriver.buildFields (.../node_modules/@mikro-orm/knex/AbstractSqlDriver.js:612:24)
    at SqliteDriver.find (.../node_modules/@mikro-orm/knex/AbstractSqlDriver.js:27:25)
    at SqlEntityManager.find (.../node_modules/@mikro-orm/core/EntityManager.js:105:43)
    at async main (.../src/index.ts:29:15)

To Reproduce
In models.ts:

import { Collection, Embeddable, Embedded, Entity, IdentifiedReference, ManyToOne, OneToMany, PrimaryKey, Property } from "@mikro-orm/core";

@Entity()
export class Cat {
    @PrimaryKey()
    name!: string;

    @ManyToOne()
    user!: IdentifiedReference<User>;
}

@Embeddable()
export class Profile {
    @Property()
    phoneNumber?: string;
}

@Entity()
export class User {
    @PrimaryKey()
    id!: string;

    @Property()
    name!: string;

    @Embedded({ hidden: true })
    profile?: Profile;

    @OneToMany(() => Cat, c => c.user, { eager: true })
    cats = new Collection<Cat>(this);
}

In index.ts:

import { LoadStrategy, MikroORM } from '@mikro-orm/core';
import { Cat, Profile, User } from './user';
import { TsMorphMetadataProvider } from '@mikro-orm/reflection';

async function main() {
  const orm = await MikroORM.init({
    dbName: ':memory:',
    type: 'sqlite',
    entities: [User, Profile, Cat],
    loadStrategy: LoadStrategy.JOINED,
    metadataProvider: TsMorphMetadataProvider,
  });
  await orm.getSchemaGenerator().execute(await orm.getSchemaGenerator().generate());

  const em = orm.em.fork();

  em.create(
    User,
    {
      id: 'TestPrimary',
      name: 'TestName',
    },
    { persist: true },
  );
  await em.flush();
  em.clear();

  console.log(await em.find(User, {})); // This line fails
}

main();

The find query fails if the above configuration is used.

Expected behavior
We should not see any errors.

Additional context
A reproducible repository can be found here.

Versions

Dependency	Version
node	16.13.1
typescript	4.5.5
mikro-orm	5.0.0
your-driver	sqlite (5.0.0)

[MikeBKemp]

I also have this issue (sqlite 5.0.0, mikro-orm 5.0.0). Having an eager 1:m or not doesn't seem to make a difference though.