I sometimes experienced exceptions like:

[GEM_ROOT]/bundler/gems/netsuite-91c78614e5eb/lib/netsuite/support/attributes.rb:14→ initialize_from_attributes_hash
[GEM_ROOT]/bundler/gems/netsuite-91c78614e5eb/lib/netsuite/records/base_ref_list.rb:15→ initialize
[GEM_ROOT]/bundler/gems/netsuite-91c78614e5eb/lib/netsuite/actions/get_select_value.rb:51→ new
[GEM_ROOT]/bundler/gems/netsuite-91c78614e5eb/lib/netsuite/actions/get_select_value.rb:51→ get_select_value

There probably are conditions where and explicit <nil> value is passed, such as when an exception is thrown on the remote side (eg when two concurrent calls are made with the same credentials).
Maybe using a different approach (http://apidock.com/rails/ActiveSupport/CoreExtensions/Array/ExtractOptions/extract_options!) could be a better solution?