UnassignedReferenceException: The variable _unitsHudButton of OpenBarricadesWindowStepNoBlock has not been assigned.
You probably need to assign the _unitsHudButton variable of the OpenBarricadesWindowStepNoBlock script in the inspector.
OpenBarricadesWindowStepNoBlock.OnShow () (at Assets/Scripts/Tutorial/TutorialSteps/OpenBarricadesWindowStepNoBlock.cs:18)
TutorialWindow.OnShowEnd () (at Assets/Scripts/Windows/TutorialWindow.cs:39)
WindowBase.Show () (at Assets/Scripts/Windows/_Main/WindowBase.cs:52)
WindowsManager.ShowWindow[TutorialWindow] (System.Object updateInfo) (at Assets/Scripts/Windows/_Main/WindowsManager.cs:77)
WindowsManager.OnNewTutorialStep (TutorialAction currentAction) (at Assets/Scripts/Windows/_Main/WindowsManager.cs:156)
TutorialManager.CompleteTutorialStep (TutorialAction tutorialAction) (at Assets/Scripts/Tutorial/TutorialManager.cs:274)
ProfileManager.AddResource (ResourceType curType, .InfInt amount, Int32 amountInt) (at Assets/Scripts/Profile/ProfileManager.cs:151)
ProfileManager.AddResource (ResourceType curType, .InfInt amount) (at Assets/Scripts/Profile/ProfileManager.cs:134)
ProfileManager.AddGold (.InfInt gold) (at Assets/Scripts/Profile/ProfileManager.cs:117)
Zenject.Signal`2[TDerived,TParam1].Fire (.TParam1 p1) (at Assets/Plugins/Zenject/Source/Signals/Signal1.cs:106)
ZombieController.ZombieModelHit (.DamageInfo damageInfo) (at Assets/Scripts/Zombies/ZombieController.cs:571)
Zombie.TakeDamage (.DamageInfo damageInfo) (at Assets/Scripts/Zombies/Zombie.cs:180)
ZombieController.TakeDamage (.DamageInfo damageInfo) (at Assets/Scripts/Zombies/ZombieController.cs:560)
ZombieCollection.DealDamageToZombie (Int32 instanceId, .DamageInfo damageInfo) (at Assets/Scripts/Zombies/ZombieCollection.cs:129)
HandController.OnUpdate () (at Assets/Scripts/Characters/Controllers/HandController.cs:228)
CharacterCollection.OnUpdate () (at Assets/Scripts/GameObjects/MonoBehs/CharacterCollection.cs:84)
GameController.Update () (at Assets/Scripts/GameObjects/MonoBehs/GameController.cs:69)