Don't execute empty commands when an item cannot be collected to a gi…

…ven item stack.

fixes #871 (technically it fixes only the symptoms, not the root cause. The root cause is probably #865

src/Inventory.zig

@@ -346,6 +346,7 @@ pub const Sync = struct { // MARK: Sync
 					for(inv._items, 0..) |invStack, slot| {
 						if(std.meta.eql(invStack.item, itemStack.item)) {
 							const amount = @min(itemStack.item.?.stackSize() - invStack.amount, itemStack.amount);
+							if(amount == 0) continue;
 							executeCommand(.{.fillFromCreative = .{.dest = .{.inv = inv, .slot = @intCast(slot)}, .item = itemStack.item, .amount = invStack.amount + amount}}, null);
 							itemStack.amount -= amount;
 							if(itemStack.amount == 0) break :outer;