All worked just fine untill I added _instanceof.

I don't understand this message at all. Just need a little guidance.

My setup is following

services:
    _defaults:
        autowire: true

    _instanceof:
        Rector\Rector\AbstractClassAwareRector:
            calls:
                - ['setClassResolver', ['@Rector\NodeAnalyzer\ClassResolver']]

    # PSR-4 autodiscovery
    Rector\:
        resource: '../../src'

And the error:

Uncaught Symfony\Component\DependencyInjection\Exception\RuntimeException: The definition "Rector\Rector\RectorCollector" has a reference to an abstract definition "abstract.instanceof.Rector\Rector\Contrib\Nette\NetteObjectToSmartTraitRector". Abstract definitions cannot be the target of references. in /var/www/Rector/vendor/symfony/dependency-injection/Compiler/CheckReferenceValidityPass.php:37

NetteObjectToSmartTraitRector is not an abstract class. Not sure if that's what Symfony thinks