From b6ba214f43b374b72067c56a30a968cfd991553e Mon Sep 17 00:00:00 2001
From: Lau Ching Jun <lauchingjun@hotmail.com>
Date: Mon, 20 Jun 2016 11:53:51 +0800
Subject: [PATCH] Use nullptr when converting to std::function if value is nil

---
 sol/function.hpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sol/function.hpp b/sol/function.hpp
index ea6aa372..38baeefb 100644
--- a/sol/function.hpp
+++ b/sol/function.hpp
@@ -105,6 +105,9 @@ namespace sol {
 
 			template<typename... Args, typename... Ret>
 			static std::function<Signature> get_std_func(types<Ret...>, types<Args...>, lua_State* L, int index = -1) {
+				if (lua_isnil(L, index) || lua_isnone(L, index)) {
+					return nullptr;
+				}
 				sol::function f(L, index);
 				auto fx = [f, L, index](Args&&... args) -> meta::return_type_t<Ret...> {
 					return f.call<Ret...>(std::forward<Args>(args)...);
@@ -114,6 +117,9 @@ namespace sol {
 
 			template<typename... FxArgs>
 			static std::function<Signature> get_std_func(types<void>, types<FxArgs...>, lua_State* L, int index = -1) {
+				if (lua_isnil(L, index) || lua_isnone(L, index)) {
+					return nullptr;
+				}
 				sol::function f(L, index);
 				auto fx = [f, L, index](FxArgs&&... args) -> void {
 					f(std::forward<FxArgs>(args)...);