on_attach for lua lsp

nvim/lua/new_lsp_conf.lua

@@ -48,6 +48,8 @@ require('mason-lspconfig').setup_handlers{
 	end,
 	['sumneko_lua'] = function()
 		require('lspconfig')["sumneko_lua"].setup {
+			on_attach = on_attach,
+			flags = lsp_flags,
 			settings = {
 				Lua = {
 					diagnostics = {