I noticed strange behaviour - #named_captures may return capture groups and #[] returns nil instead of raising IndexError in the following scenario:

1. call a scanning method with a Regexp (with named capture groups)
2. call a scanning method without a Regexp pattern (#getch, #get_byte or #scan_until/#exist?/... with a String pattern)
3. call #[] with a named capture group (used in the Regexp) and #named_captures

I would expect that #[] raises IndexError and #named_captures returns nil.

Example

require 'strscan' s = StringScanner.new('Fri Dec 12 1975 14:39') s.scan(/(?<wday>Fri)/) p s.named_captures # => {"wday" => "Fri"} p s["wday"] # => "Fri" s.get_byte p s.named_captures # => {"wday" => nil} p s["wday"] # => nil s["month"] # => undefined group name reference: month (IndexError)

Wondering whether it's correct behaviour.