Wait for ajax breaks tests

[golddragon007]

I have several scenarios where I get the following error message: Fatal error: Call to a member function execute() on null
This causing it: https://github.com/jhedstrom/drupalextension/blob/master/src/Drupal/DrupalExtension/Context/MinkContext.php#L106
With a combination of the following step name:
Given I am logged in as "B User to follow"
As this is the first command in the scenario and the selenium browser is not yet populated, I get an error.

[golddragon007]

The wait function should be only called when the session is already running (started).
$this->getSession()->getDriver()->isStarted()