Set placer to nil instead of a non-functional one in item_OnPlace (#6449)

* Set placer to nil instead of a non-functional one

This requires nil checks in core.rotate_node and core.rotate_and_place.

builtin/common/misc_helpers.lua

@@ -349,7 +349,7 @@ if INIT == "game" then
 					itemstack, pointed_thing)
 			return
 		end
-		local fdir = core.dir_to_facedir(placer:get_look_dir())
+		local fdir = placer and core.dir_to_facedir(placer:get_look_dir()) or 0
 		local wield_name = itemstack:get_name()
 
 		local above = pointed_thing.above
@@ -369,9 +369,9 @@ if INIT == "game" then
 			iswall = false
 		end
 
-		if core.is_protected(pos, placer:get_player_name()) then
-			core.record_protection_violation(pos,
-					placer:get_player_name())
+		local name = placer and placer:get_player_name() or ""
+		if core.is_protected(pos, name) then
+			core.record_protection_violation(pos, name)
 			return
 		end
 
@@ -432,9 +432,11 @@ if INIT == "game" then
 	end
 
 	core.rotate_node = function(itemstack, placer, pointed_thing)
+		local name = placer and placer:get_player_name() or ""
+		local invert_wall = placer and placer:get_player_control().sneak or false
 		core.rotate_and_place(itemstack, placer, pointed_thing,
-				is_creative(placer:get_player_name()),
-				{invert_wall = placer:get_player_control().sneak})
+				is_creative(name),
+				{invert_wall = invert_wall})
 		return itemstack
 	end
 end

src/script/cpp_api/s_item.cpp

@@ -69,7 +69,12 @@ bool ScriptApiItem::item_OnPlace(ItemStack &item,
 
 	// Call function
 	LuaItemStack::create(L, item);
-	objectrefGetOrCreate(L, placer);
+
+	if (!placer)
+		lua_pushnil(L);
+	else
+		objectrefGetOrCreate(L, placer);
+
 	pushPointedThing(pointed);
 	PCALL_RES(lua_pcall(L, 3, 1, error_handler));
 	if (!lua_isnil(L, -1)) {

src/script/lua_api/l_env.cpp

@@ -396,9 +396,8 @@ int ModApiEnvMod::l_place_node(lua_State *L)
 	pointed.type = POINTEDTHING_NODE;
 	pointed.node_abovesurface = pos;
 	pointed.node_undersurface = pos + v3s16(0,-1,0);
-	// Place it with a NULL placer (appears in Lua as a non-functional
-	// ObjectRef)
-	bool success = scriptIfaceItem->item_OnPlace(item, NULL, pointed);
+	// Place it with a NULL placer (appears in Lua as nil)
+	bool success = scriptIfaceItem->item_OnPlace(item, nullptr, pointed);
 	lua_pushboolean(L, success);
 	return 1;
 }