Improve Script CPP API diagnostics

src/script/common/c_internal.cpp

src/script/common/c_internal.h

src/script/cpp_api/s_async.cpp

src/script/cpp_api/s_base.cpp

src/script/cpp_api/s_base.h

src/script/cpp_api/s_entity.cpp

src/script/cpp_api/s_inventory.cpp

src/script/cpp_api/s_item.cpp

src/script/cpp_api/s_mainmenu.cpp

src/script/cpp_api/s_node.cpp

src/script/cpp_api/s_nodemeta.cpp

src/script/cpp_api/s_player.cpp

src/script/cpp_api/s_server.cpp

src/script/lua_api/l_env.cpp

src/script/scripting_game.cpp

src/script/scripting_game.h