/**
* Removes a link between an activity and an ability or a competency.
*
* @param Activity $activity
* @param Ability|Competency $target
* @throws \InvalidArgumentException if the target isn't an instance of Ability or Competency
* @throws \LogicException if the link doesn't exists
*/
public function removeLink(Activity $activity, $target)
{
if (!$target instanceof Ability && !$target instanceof Competency) {
throw new \InvalidArgumentException('Second argument must be a Competency or an Ability instance');
}
if (!$target->isLinkedToActivity($activity)) {
throw new \LogicException("There's no link between activity {$activity->getId()} and target {$target->getId()}");
}
$target->removeActivity($activity);
$this->om->flush();
}
