Handle empty result set in variants_option_values ransacker

Updated the `variants_option_values` ransacker to handle scenarios where
there are no matching product IDs.
By leveraging the `.presence` method, we ensure that the ransacker returns `nil`
instead of an empty array when there are no results.
This prevents potential SQL syntax errors across different database systems.

Author: rainerdema

core/app/models/spree/product.rb

@@ -143,6 +143,7 @@ def find_or_build_master
         .where(spree_option_values: { id: v })
         .distinct
         .pluck(:id)
+        .presence
     } do |parent|
       parent.table[:id]
     end

core/spec/models/spree/product_spec.rb

@@ -662,6 +662,12 @@ class Extension < Spree::Base
       expect(result).to contain_exactly(product_1, product_2)
     end
 
+    it "returns no products if there is no match" do
+      non_existing_option_value_id = 99999
+      result = Spree::Product.ransack(variants_option_values_in: [non_existing_option_value_id]).result
+      expect(result).to be_empty
+    end
+
     it "returns products that match any of the provided option value IDs" do
       product_1 = create(:product)
       product_2 = create(:product)