MissingReferenceException: The variable _MaterialUIPrefab of MenuMaterialsPanel doesn't exist anymore.
You probably need to reassign the _MaterialUIPrefab variable of the 'MenuMaterialsPanel' script in the inspector.
UnityEngine.Object.Instantiate[GameObject] (UnityEngine.GameObject original) (at C:/buildslave/unity/build/Runtime/Export/UnityEngineObject.cs:201)
Nekki.SF2.GUI.Menu.MenuMaterialsPanel.CreateMaterial (Nekki.SF2.Core.Utils.GameCurrency p_material) (at Assets/src/GUI/Scenes/Dojo/MenuMaterialsPanel.cs:33)
Nekki.SF2.GUI.Menu.MenuMaterialsPanel.CreateMaterials () (at Assets/src/GUI/Scenes/Dojo/MenuMaterialsPanel.cs:26)
Nekki.SF2.GUI.Menu.MenuMaterialsPanel.Init () (at Assets/src/GUI/Scenes/Dojo/MenuMaterialsPanel.cs:18)
Nekki.SF2.GUI.Menu.MainMenu.Init () (at Assets/src/GUI/Scenes/Dojo/MainMenu.cs:215)
Nekki.SF2.GUI.UIModule.Activate () (at Assets/src/GUI/UIModule.cs:80)
Nekki.SF2.GUI.UIModule.MountModule (Nekki.SF2.GUI.UIModule p_pref, UnityEngine.Transform p_parent, Boolean p_active) (at Assets/src/GUI/UIModule.cs:38)
Nekki.SF2.GUI.ModuleHolder.MountModules () (at Assets/src/GUI/ModuleHolder.cs:145)
Nekki.SF2.GUI.ModuleHolder.PreInit () (at Assets/src/GUI/ModuleHolder.cs:100)
Nekki.SF2.GUI.Scene`1[T].PreInit () (at Assets/src/GUI/Scene.cs:70)
Nekki.SF2.GUI.Scene`1+<PreInitWait>c__Iterator0[Nekki.SF2.GUI.Map.MapScene].MoveNext () (at Assets/src/GUI/Scene.cs:52)
UnityEngine.SetupCoroutine.InvokeMoveNext (IEnumerator enumerator, IntPtr returnValueAddress) (at C:/buildslave/unity/build/Runtime/Export/Coroutines.cs:17)