more general fix

diff --git a/AIResearchGrid.lua b/AIResearchGrid.lua
index 7008ec6..05cdf80 100644
--- a/AIResearchGrid.lua
+++ b/AIResearchGrid.lua
@@ -610,7 +610,7 @@ function AIRG.PopulateAll()
 		end

 		for i = 15 ,20  do	-- helps stop crashes when new styles are added
-			if AIRG.vars.styles[thisname][i] == nil then
+			if type(AIRG.vars.styles[thisname][i]) ~= "table"  then
 				AIRG.vars.styles[thisname][i] = {}
 			end
 		end