fermenter: return items to source inventory when faulted.

Items should be moved back to source inventory when machine fails
due to incorrect type of items there (game internal error).

Unused local variable removed.

Signed-off-by: Michal Cieslakiewicz <michal.cieslakiewicz@wp.pl>

tubelib_addons1/fermenter.lua

@@ -116,11 +116,13 @@ local function convert_leaves_to_biogas(pos, meta)
 	
 	-- take NUM_LEAVES items
 	local items = {}
-	local fault = false
 	for i = 1, NUM_LEAVES do
 		items[i] = tubelib.get_num_items(meta, "src", 1)
 		if items[i] then  -- input available?
 			if not is_leaves(items[i]:get_name()) then
+				for j = 1, #items do
+					inv:add_item("src", items[j])
+				end
 				State:fault(pos, meta)
 				return
 			end