#346 Quickfix indexing nil savetable in doc/doc

mods/HELP/doc/doc/init.lua

@@ -611,6 +611,8 @@ do
 		io.close(file)
 		if string then
 			local savetable = minetest.deserialize(string)
+			local players_stored_data = savetable and savetable.players_stored_data
+			if players_stored_data then
 				for name, players_stored_data in pairs(savetable.players_stored_data) do
 					doc.data.players[name] = {}
 					doc.data.players[name].stored_data = players_stored_data
@@ -618,6 +620,7 @@ do
 				minetest.log("action", "[doc] doc.mt successfully read.")
 			end
 		end
+	end
 end
 
 function doc.save_to_file()