Fix manifest generation for playlist item with deleted source

Gemfile.lock

@@ -67,7 +67,7 @@ GIT
 
 GIT
   remote: https://github.com/samvera-labs/iiif_manifest.git
-  revision: c8ca0c6e54517446419c20221260eaf3dcf46d4e
+  revision: c7467b4ae32934f161bd2cabdd741ec9293cefe6
   branch: main
   specs:
     iiif_manifest (1.3.1)

app/models/iiif_playlist_canvas_presenter.rb

@@ -40,13 +40,15 @@ def master_file
   end
 
   def part_of
+    return if master_file.nil?
     [{
       "@id" => Rails.application.routes.url_helpers.manifest_media_object_url(master_file.media_object_id).to_s,
       "type" => "manifest"
     }]
   end
 
   def item_metadata
+    return if master_file.nil?
     [
       metadata_field('Title', master_file.media_object.title),
       metadata_field('Date', master_file.media_object.date_issued),

spec/controllers/playlists_controller_spec.rb

@@ -618,5 +618,17 @@
           expect(parsed_response['items'][1]['items'][0].keys).to_not include 'items'
         end
       end
+
+      context "playlist item with deleted source" do
+        before do
+          master_file.delete
+        end
+
+        it "returns a blank canvas" do
+          get :manifest, format: 'json', params: { id: playlist.id }, session: valid_session
+          parsed_response = JSON.parse(response.body)
+          expect(parsed_response['items'][0]['items'][0].keys).to_not include 'items'
+        end
+      end
     end
   end