@Output childEvent not initialized

I believe the problem is in your import import { EventEmitter } from 'events'; is not the one you should import here. Try changing the import to import { EventEmitter } from '@angular/core';

UPDATE

Here's a stackblitz example showing that it works

With Angular newer versions, like 8 you have to:

1. Import correctly Emitter as k.s. said: import { EventEmitter } from '@angular/core'
2. Initialize the emitter for Output: @Output() emisor = new EventEmitter<type>();