Fix unit dead check

UI doesn't have .Dead

There's an error spam when selected ACU or Nuke is killed / deleted, which triggers cinematics

Author: speed2CZ

lua/ui/game/orders.lua

@@ -891,7 +891,7 @@ local function disPauseFunc()
 end
 
 local function NukeBtnText(button)
-    if not currentSelection[1] or currentSelection[1].Dead then return '' end
+    if not currentSelection[1] or IsDestroyed(currentSelection[1]) then return '' end
     if table.getsize(currentSelection) > 1 then
         button.buttonText:SetColor('fffff600')
         return '?'
@@ -907,7 +907,7 @@ local function NukeBtnText(button)
 end
 
 local function TacticalBtnText(button)
-    if not currentSelection[1] or currentSelection[1].Dead then return '' end
+    if not currentSelection[1] or IsDestroyed(currentSelection[1]) then return '' end
     if table.getsize(currentSelection) > 1 then
         button.buttonText:SetColor('fffff600')
         return '?'
@@ -999,7 +999,7 @@ end
 
 function EnterOverchargeMode()
     local unit = currentSelection[1]
-    if not unit or unit.Dead or unit:IsOverchargePaused() then return end
+    if not unit or IsDestroyed(unit) or unit:IsOverchargePaused() then return end
     local bp = unit:GetBlueprint()
     local weapon = FindOCWeapon(unit:GetBlueprint())
     if not weapon then return end
@@ -1012,7 +1012,7 @@ end
 
 local function OverchargeFrame(self, deltaTime)
     local unit = currentSelection[1]
-    if not unit or unit.Dead then return end
+    if not unit or IsDestroyed(unit) then return end
     local weapon = FindOCWeapon(unit:GetBlueprint())
     if not weapon then
         self:SetNeedsFrameUpdate(false)