add method to blank invalid non setup fields

app/models/log.rb

@@ -52,6 +52,16 @@ class Log < ApplicationRecord
     form.end_date > Time.zone.today
   end
 
+  def blank_invalid_non_setup_fields!
+    setup_ids = form.setup_sections.flat_map(&:subsections).flat_map(&:questions).map(&:id)
+
+    errors.each do |error|
+      next if setup_ids.include?(error.attribute.to_s)
+
+      public_send("#{error.attribute}=", nil)
+    end
+  end
+
 private
 
   def update_status!

spec/models/lettings_log_spec.rb

@@ -2536,4 +2536,24 @@ RSpec.describe LettingsLog do
       end
     end
   end
+
+  describe "#blank_invalid_non_setup_fields!" do
+    context "when a setup field is invalid" do
+      subject(:model) { described_class.new(needstype: 404) }
+
+      it "does not blank it" do
+        model.valid?
+        expect { model.blank_invalid_non_setup_fields! }.not_to change(model, :needstype)
+      end
+    end
+
+    context "when a non setup field is invalid" do
+      subject(:model) { described_class.new(beds: 404) }
+
+      it "blanks it" do
+        model.valid?
+        expect { model.blank_invalid_non_setup_fields! }.to change(model, :beds)
+      end
+    end
+  end
 end