Fix startup NullReferenceException on WorldBox 0.51.2 (resilient power-tab lookup)

[Skilvin]

Problem

On WorldBox 0.51.2 (build 719@5dec), starting the game with mods enabled crashes during NML's vanilla-tab reconstruction:

System.NullReferenceException: Object reference not set to an instance of an object
  at NeoModLoader.General.UI.Tab.WrappedPowersTab..ctor (PowersTab pPowersTab) [0x00015]
  at NeoModLoader.General.UI.Tab.TabMain.InitTab ()
  at NeoModLoader.General.UI.Tab.ReconstructedVanillaTab.Init ()
  at NeoModLoader.General.UI.Tab.TabManager._init ()

Root cause

PowerButtonCreator.GetTab(pId) locates the tab through a hard-coded UI hierarchy path:

CanvasBottom/BottomElements/BottomElementsMover/CanvasScrollView/Scroll View/Viewport/Content/Power Tabs/{pId}

In 0.51.2 this hierarchy changed, so transform.Find(...) returns null, GetTab returns null, and new WrappedPowersTab(null) throws an NRE on Tab.name.

Changes

1. general/PowerButtonCreator.cs — GetTab: keep the fast hard-coded path, but fall back to locating the tab by its GameObject name via Resources.FindObjectsOfTypeAll<PowersTab>() when the path no longer matches. This makes the lookup resilient to UI-hierarchy changes.
2. general/ui/tab/WrappedPowersTab.cs — constructor: add a null guard so the wrapper never NREs even if a tab is still not found (sets Modifiable = false and returns early).

Testing

Built in Debug and tested in-game on WorldBox 0.51.2 (experimental):

• no more WrappedPowersTab..ctor NRE at boot,
• power tabs reconstruct correctly,
• vanilla + modded power buttons present.