Avoid "loop is executed at most once" warning

mods/db/init.lua

@@ -72,11 +72,12 @@ function db.player_get_meta(name)
 		SELECT meta FROM player WHERE name = :name
 	]]
 	stmt:bind_names{name = name}
-	for row in stmt:nrows() do
+	local it, state = stmt:nrows()
+	local row = it(state)
 	stmt:finalize()
+	if row then
 		return minetest.parse_json(row.meta)
 	end
-	stmt:finalize()
 
 	print("no such player in db", name)
 	return nil
@@ -102,11 +103,12 @@ function db.box_get_data(box_id)
 		SELECT data FROM box WHERE id = :box_id
 	]]
 	stmt:bind_names{box_id = box_id}
-	for row in stmt:nrows() do
+	local it, state = stmt:nrows()
+	local row = it(state)
 	stmt:finalize()
+	if row then
 		return row.data
 	end
-	stmt:finalize()
 
 	print("no such box in db", box_id)
 	return nil