Show selected unit in legacy build menu pre-game (#3963)

* Show selected unit in legacy build menu pre-game

- Use correct lookup table: `units.unitName` is always empty, but there is a table local to this file that can be used.
- Do not invert the build command ID, the names are keyed by positive ID.

* Remove unused unitName

Table was not initialized nor referenced

---------

Co-authored-by: Rhys van der Waerden <>

luaui/Widgets/gui_buildmenu.lua

@@ -746,9 +746,8 @@ function widget:DrawScreen()
 
 	if Spring.GetGameFrame() == 0 and WG['pregame-build'] then
 		activeCmd = WG["pregame-build"] and WG["pregame-build"].getPreGameDefID()
-		activeCmd = activeCmd and -activeCmd
 		if activeCmd then
-			activeCmd = units.unitName[activeCmd]
+			activeCmd = unitName[activeCmd]
 		end
 	else
 		activeCmd = select(4, spGetActiveCommand())

luaui/configs/unit_buildmenu_config.lua

@@ -4,7 +4,6 @@
 ---
 
 
-local unitName = {}
 local unitEnergyCost = {}
 local unitMetalCost = {}
 local unitGroup = {}
@@ -163,8 +162,6 @@ local minWaterUnitDepth = -11
 ------------------------------------
 
 return {
-
-	unitName = unitName,
 	unitEnergyCost = unitEnergyCost,
 	unitMetalCost = unitMetalCost,
 	unitGroup = unitGroup,