After the demo mode has expired, if you try to place a block, it will disappear from your inventory.

Steps to reproduce:

1. Create a new demo world
2. Get yourself a few blocks
3. Change 'Time' in level.dat_old and level.dat to 120485
4. Notice that despite a block not actually being placed, it disappears from your inventory on client-side

Expected result:

Blocks that failed to place shouldn't disappear from inventory on client-side

Observed result:

Blocks that failed to place disappear from inventory on client-side

Note:

If you reload the world the items will reappear.