Thrown by BTree.buildFrom when its input is not strictly ascending by the comparator - either an out-of-order pair (compare > 0) or a duplicate (compare === 0). The message names the offending pair.
Optional
Thrown by BTree.buildFrom when its input is not strictly ascending by the comparator - either an out-of-order pair (compare > 0) or a duplicate (compare === 0). The message names the offending pair.