manually registered subscribers not called from transactional

[zoltan-mihalyi]

Describe the bug
When i register the subscriber manually using em.getEventManager().registerSubscriber(this) the event handlers are not called when events are happening in a transactional callback.

To Reproduce
Steps to reproduce the behavior:

1. Make the following NestJS service:

import type { EventSubscriber } from '@mikro-orm/core';
import { EntityManager } from '@mikro-orm/postgresql';
import { Injectable } from '@nestjs/common';
import User from '../entities/User';

@Injectable()
export default class MyService implements EventSubscriber<User> {
    public constructor(private em: EntityManager) {
        em.getEventManager().registerSubscriber(this);
        console.log('subscribed');
        this.test();
    }

    public onFlush() {
        console.log('onFlush');
    }

    public async test() {
        await this.em.transactional(async (em) => {
            const user = this.em.getRepository(User).create({});
            em.persist(user);
        });
    }
}

3. Instantiate the service (either manually or by NestJS)
4. "subscribed" is logged, but "onFlush" is not.

Expected behavior
Event handlers should be called and onFlush

Additional context
I figured out that in EntityManager.ts, there is this code:

   // in transactional:
    const fork = em.fork({
      clear: false, // state will be merged once resolves
      flushMode: options.flushMode,
      freshEventManager: true,
    });
    
    //in fork:
    const eventManager = options.freshEventManager ? new EventManager(em.config.get('subscribers')) : em.eventManager;

which means that the fresh event manager uses subscribers from config, but ignores subscribers registered via registerSubscriber()

Versions

Dependency	Version
node	16.13.2
typescript	4.6.2
mikro-orm	5.4.2
your-driver	postgresql

[zoltan-mihalyi]

For the record: it was fixed in commit: 0e523b3

And will be released in v5.6.1