outOfRange method

String outOfRange(String inner, int count, int index)

An nth index past the end of what its target matched.

Both halves are named because both are wrong in different calls, and the exception underneath tells them apart badly: elementAt says "no indices are valid" when the target matched zero widgets, which never mentions the count that is the actual problem, and reads like a complaint about the index when the index is the one part that was fine.

Implementation

String outOfRange(String inner, int count, int index) =>
    '$inner matches $count widget${count == 1 ? '' : 's'}, so `nth` index '
    '$index is out of range: '
    '${count == 1 ? 'the only index is 0' : 'valid indices are 0–${count - 1}'}.';