title: Codeception actor not found exception
body: <p>When running <code>codecept run -vvv</code> I get an error stating that the actor is undefined in the SuiteManager class (method is initialize).
  Any guess on how to fix this?</p>
  
  <p>I've set up two basic unit tests where I just want to assert some values, and they worked until I switched to the composer autoloader.</p>
  
  <p><a href="https://i.stack.imgur.com/ZZAlA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZZAlA.png" alt="Error log"></a></p>
  
  <p>In the composer.json I have the following:</p>
  
  <p><code>"autoload": {
      "classmap": [
        "app"
      ]
    },
    "require-dev": {
      "codeception/codeception": "^2.3",
      "phpstan/phpstan": "^0.8.0",
      "symfony/console": "^3.3"
    }</code></p>
  
  <p>In the main _bootstrap file provided by Codeception I only have a require_once for the vendor autoloader file.
  Using php 7.1 and latest versions of the packages.</p>