🐛 Fix SequenceSet#[] -> nil for invalid start - #777

🐛 Fix SequenceSet#[] -> nil for invalid start#777

nevans wants to merge 3 commits into

sequence_set/fix-slice-range-pos-to-out-of-range-negruby/net-imap:sequence_set/fix-slice-range-pos-to-out-of-range-negfrom

sequence_set/fix-slice-empty-set-from-cardinalityruby/net-imap:sequence_set/fix-slice-empty-set-from-cardinalityCopy head branch name to clipboard