Fix commentaire file_url generator

app/uploaders/remote_downloader.rb

@@ -4,7 +4,9 @@ class RemoteDownloader
   end
 
   def url
-    @url ||= File.join(base_url, CarrierWave::Uploader::Base.fog_directory, @filename)
+    if @filename.present?
+      @url ||= File.join(base_url, CarrierWave::Uploader::Base.fog_directory, @filename)
+    end
   end
 
   protected

spec/uploaders/remote_downloader_spec.rb

@@ -7,5 +7,11 @@ describe RemoteDownloader do
 
   describe '#url' do
     it { expect(subject.url).to eq 'https://static.demarches-simplifiees.fr/tps_dev/file_name.pdf' }
+
+    context 'no filename' do
+      let(:filename) { nil }
+
+      it { expect(subject.url).to be_nil }
+    end
   end
 end