Read access violation when loading scene after authorizing ion token

[csciguy8]

• Open Unreal Editor (5.3.2, Windows 10)

• Play around with unreal samples level, 04_MAIN_CesiumSublevels.umap

• Open level, 12_CesiumGoogleMapsTiles.umap

• Ion dialog popped up to allow me to specify a valid token (mine was invalid)

• Click "Authorize this token"

• Observe crash (debug build)

Odd things:

• It crashes in ::removeCollisionForTiles iterating over a tile in the list, yet pResult->tilesFadingOut is currently empty
• this->_pTileset is nullptr, suggesting it was destroyed while ::Tick was executing

(was running from this branch, although this crash looks unrelated to the branch changes)