error-handling code snippets in ruby

fix: `series = struct.new(:str) { def slices(n) n > @str.length ? argumenterror.new("no!") : str.each_char.each_cons(n).map(&:join) end }` in ruby

how to sum [{ a: 5, b: 10, c: 15 }, {}, {q: 67}] such the i don't get the "undefined method `values' for nil:nilclass" error in ruby