Several models have invalid "name" included in ransackable_attributes

[mdesantis]

I stumbled upon a Ransack misconfiguration:

solidus/core/app/models/concerns/spree/ransackable_attributes.rb

Line 10 in 4d53bdc

self.default_ransackable_attributes = %w[id name]

name is included by default in all the models, even the ones which don't have a name column, such as Spree::Variant, causing Ransack searches like this:

Spree::Variant.ransack('name_cont' => 'asd', 's' => 'id desc').result.to_sql

fail with the following error:

> bundle exec rails c
Loading development environment (Rails 5.2.3)
[1] pry(main)> Spree::Variant.ransack('name_cont' => 'asd', 's' => 'id desc').result.to_sql
NoMethodError: undefined method `type' for nil:NilClass
from gems/ransack-2.1.1/lib/ransack/adapters/active_record/context.rb:28:in `type_for'

Instead of discarding the name matcher.

Solidus Version: 2.9.0.alpha@4d53bdc92

To Reproduce

cd sandbox
bundle exec rails r "puts Spree::Variant.ransack('name_cont' => 'asd', 's' => 'id desc').result.to_sql"

Current behavior

undefined method `type' for nil:NilClass

Expected behavior

SELECT "spree_variants".* FROM "spree_variants" WHERE "spree_variants"."deleted_at" IS NULL ORDER BY "spree_variants"."id" DESC