[pob1-port] Slighty better nil checks for missing API function (#1577)

* Apply changes from PathOfBuildingCommunity/PathOfBuilding#9128

* Fix conflicts

---------

Co-authored-by: Nightblade <Nightblade@users.noreply.github.com>
Co-authored-by: LocalIdentity <localidentity2@gmail.com>

Author: 3 people

src/HeadlessWrapper.lua

@@ -51,6 +51,10 @@ end
 function GetScreenScale()
 	return 1
 end
+function GetDPIScaleOverridePercent()
+	return 1
+end
+function SetDPIScaleOverridePercent(scale) end
 function SetClearColor(r, g, b, a) end
 function SetDrawLayer(layer, subLayer) end
 function SetViewport(x, y, width, height) end

src/Modules/Main.lua

@@ -113,6 +113,8 @@ function main:Init()
 	self.showFlavourText = true
 	self.showAnimations = true
 	self.errorReadingSettings = false
+	
+	if not SetDPIScaleOverridePercent then SetDPIScaleOverridePercent = function(scale) end end
 
 	if launch.devMode and IsKeyDown("CTRL") or os.getenv("REGENERATE_MOD_CACHE") == "1" then
 		-- If modLib.parseMod doesn't find a cache entry it generates it.