Exception raised when an aggregate operation needs every member of an interval set whose backend is unbounded (a lazy generator such as Tempo.weekends/1).

Unbounded sets support the walking operations — Enum.take/2, Tempo.IntervalSet.walk/1, covered?/2, first/1, and use as a skipping: busy set — but any operation whose answer requires the whole member list (to_list/1, count/1, coalesce/1, set algebra) refuses rather than walking forever. Bound the set first: intersect the walk with a finite span, or take the members you need.