Hello ^^

In my Simple Turrets mod I am getting errors when I upgrade, where there were none before.

GetInspectString exception on Turret_STEMPTurret26414:
System.NullReferenceException: Object reference not set to an instance of an object
at TurretExtensions.CompUpgradable.CompInspectStringExtra () [0x000c1] in <dd43e0d936e7407a893091afd6fbc430>:0
at Verse.ThingWithComps.InspectStringPartsFromComps () [0x00020] in <29684bdca4b441d38f64a3f064edc8ed>:0
at Verse.ThingWithComps.GetInspectString () [0x00013] in <29684bdca4b441d38f64a3f064edc8ed>:0
at (wrapper dynamic-method) RimWorld.Building_TurretGun.DMD<DMD<GetInspectString_Patch0>?-1438745600::GetInspectString_Patch0>(RimWorld.Building_TurretGun)
at RimWorld.InspectPaneFiller.DrawInspectStringFor (Verse.ISelectable sel, UnityEngine.Rect rect) [0x00000] in <29684bdca4b441d38f64a3f064edc8ed>:0
Verse.Log:Error(String, Boolean)
RimWorld.InspectPaneFiller:DrawInspectStringFor(ISelectable, Rect)
RimWorld.InspectPaneFiller:DoPaneContentsFor(ISelectable, Rect)
RimWorld.MainTabWindow_Inspect:DoPaneContents(Rect)
RimWorld.InspectPaneUtility:InspectPaneOnGUI(Rect, IInspectPane)
RimWorld.MainTabWindow_Inspect:DoWindowContents(Rect)
Verse.Window:InnerWindowOnGUI(Int32)
UnityEngine.GUI:CallWindowDelegate(WindowFunction, Int32, Int32, GUISkin, Int32, Single, Single, GUIStyle)


https://gist.github.com/259a0d38fa0f938c36780a061bd8df49

It happens right when I try to upgrade a turret.