Xeroizer::Record::Base#to_h converts nil values into empty hashes

[drewish]

I'd been trying use to_h to get hashes that I could use slice on but ran into a kind of odd issue where values that were nil on the Xero object turned into {} in the hash. Turns out:

irb(main):001:0> nil.to_h
=> {}

So it seems buggy that we're not handling nil values separately in the to_h:

xeroizer/lib/xeroizer/record/base.rb

Line 143 in 7de4747

[k, v.kind_of?(Array) ? v.map(&:to_h) : (v.respond_to?(:to_h) ? v.to_h : v)]