chore: Prevent null in Contact JSONB attributes (#3730)

db/migrate/20220111200105_update_nil_contact_attributes_to_empty_hash.rb

@@ -0,0 +1,8 @@
+class UpdateNilContactAttributesToEmptyHash < ActiveRecord::Migration[6.1]
+  def change
+    # rubocop:disable Rails/SkipsModelValidations
+    Contact.where(custom_attributes: nil).update_all(custom_attributes: {})
+    Contact.where(additional_attributes: nil).update_all(additional_attributes: {})
+    # rubocop:enable Rails/SkipsModelValidations
+  end
+end