Removed reference to AssertionError. Inlined strings in SackChange validation to minimise potential allocations. Avoided generator allocations in ThroughSequence by using explicit indexing/incrementing
Removed reference to AssertionError. Inlined strings in SackChange validation to minimise potential allocations. Avoided generator allocations in ThroughSequence by using explicit indexing/incrementing

cefn/avatap,cefn/avatap