Fix isNan on setYaw Lua call (#7380)

* Fix isNan on setYaw Lua call

src/script/lua_api/l_base.h

@@ -69,4 +69,6 @@ class ModApiBase {
 			const char* name,
 			lua_CFunction func,
 			int top);
+
+	static bool isNaN(lua_State *L, int idx);
 };