use t_concat in both implementations

Author: tst2005

require.lua

@@ -84,7 +84,7 @@ local function require52 (name)
         loader = nil
     end
     if loader == nil then
-        error("module '" .. name .. "' not found: "..table.concat(msg), 2)
+        error("module '" .. name .. "' not found: "..t_concat(msg), 2)
     end
     local res = loader(name, param)
     if res ~= nil then