Itemsaver drops tools on the ground

[graemeg]

Describe the bug
In the InventoryManager I enable ItemSaver. I build nether tunnels and have 5 pickaxes in my toolbar and would like to preserve them (not let them break). While digging, my inventory gets full of netherrack. When the tool reaches its durability limit, Lamba Client drops the tool on the ground, switches to another tool and keeps digging (yes, I use Lambda in combination with HighwayTools plugin).

To Reproduce
Exactly as described above

1. Place 2 or more pickaxes in the hotbar
2. Fill all of the inventory with Netherrack and free hotbar slots
3. Activate item saver with whatever durability setting
4. Activate HightwayTools to start using the items.
5. When the first pickaxe reaches it's durability, it's dropped on the ground. It can't be picked up because inventory is full.

Expected behavior
Swap to another tool of the same type in the hotbar, or swap to another tool of the same type in your inventory. Don't drop the tool on the ground.

Debug info
n/a

Additional context / media
n/a

[graemeg]

I know about the InventoryManager option to auto eject items (leaving one slot open). Unfortunately that is a very unreliable solution. I still see many cases where netherrack popped back into my inventory at the same time Lambda tries to switch to another tool. At that instant it can't find a free slot, then drops the tool on the ground. And if you use that in combination with HighwayTools where you keep moving forward while digging, you will have moved past your tool on the ground, thus it's lost. 😞

Maybe if it could always keep 2 slots open (not just one), then it should drastically reduce the chance of dropping your tools.