[BUG] Investigate freelist test scenario

[travisvroman]

Copied from a comment on YT:

During testing I encountered case where allocated space at the end did not get freed.
Steps I used:

• make freelist for 3-4 elements and allocate all of them
• free last one (this will hit the case you described in the next video)
• free something else
  last operation should return false (at least for me it does). Offset is less than the only free block in the free list.

To fix that I did add some logic after while loop to fix that, but it seemed a bit hacky.