Assert some variable types obtained from lua automation

advtrains/advtrains_luaautomation/atc_rail.lua

@@ -48,6 +48,7 @@ function r.fire_event(pos, evtdata)
 	local customfct={
 		atc_send = function(cmd)
 			if not train_id then return false end
+			assertt(cmd, "string")
 			advtrains.atc.train_reset_command(train_id)
 			train.atc_command=cmd
 			train.atc_arrow=atc_arrow
@@ -55,6 +56,7 @@ function r.fire_event(pos, evtdata)
 		end,
 		atc_reset = function(cmd)
 			if not train_id then return false end
+			assertt(cmd, "string")
 			advtrains.atc.train_reset_command(train_id)
 			return true
 		end,
@@ -63,11 +65,13 @@ function r.fire_event(pos, evtdata)
 		atc_speed = tvel,
 		atc_set_text_outside = function(text)
 			if not train_id then return false end
+			if text then assertt(text, "string") end
 			advtrains.trains[train_id].text_outside=text
 			return true
 		end,
 		atc_set_text_inside = function(text)
 			if not train_id then return false end
+			if text then assertt(text, "string") end
 			advtrains.trains[train_id].text_inside=text
 			return true
 		end,

advtrains/advtrains_luaautomation/init.lua

@@ -16,6 +16,13 @@ atlatc = { envs = {}}
 
 minetest.register_privilege("atlatc", { description = "Player can place and modify LUA ATC components. Grant with care! Allows to execute bad LUA code.", give_to_singleplayer = false, default= false })
 
+--assertt helper. error if a variable is not of a type
+function assertt(var, typ)
+	if type(var)~=typ then
+		error("Assertion failed, variable has to be of type "..typ)
+	end
+end
+
 local mp=minetest.get_modpath("advtrains_luaautomation")
 if not mp then
 	error("Mod name error: Mod folder is not named 'advtrains_luaautomation'!")