SingleUseLinksViewerController current_ability behavior fixes

app/controllers/hyrax/single_use_links_viewer_controller.rb

@@ -84,7 +84,13 @@ def asset
     end
 
     def current_ability
-      @current_ability ||= SingleUseLinksViewerController::Ability.new current_user, single_use_link
+      link_instance = nil
+      begin
+        link_instance = single_use_link
+      rescue ActiveRecord::RecordNotFound
+        Rails.logger.debug("Single user link was not found while getting current ability")
+      end
+      @current_ability ||= SingleUseLinksViewerController::Ability.new current_user, link_instance
     end
 
     def render_single_use_error(exception)
@@ -102,9 +108,10 @@ class Ability
       include CanCan::Ability
 
       attr_reader :single_use_link
+      attr_reader :current_user
 
       def initialize(user, single_use_link)
-        @user = user || ::User.new
+        @current_user = user || ::User.new
         return unless single_use_link
 
         @single_use_link = single_use_link

spec/controllers/hyrax/single_use_links_viewer_controller_spec.rb

@@ -64,5 +64,19 @@
         expect(response).to render_template("hyrax/single_use_links_viewer/single_use_error", "layouts/error")
       end
     end
+
+    describe "#current_ability" do
+      context "when the key is not found" do
+        before { SingleUseLink.find_by_download_key!(show_link_hash).destroy }
+
+        it "returns the current ability" do
+          expect(subject.send(:current_ability)).to be_present
+        end
+
+        it "returns the current user" do
+          expect(subject.send(:current_ability).current_user).to be_present
+        end
+      end
+    end
   end
 end