Validate existence of artifacts in ArtifactsController, render 404 if not found

app/controllers/projects/artifacts_controller.rb

 class Projects::ArtifactsController < Projects::ApplicationController
   layout 'project'
   before_action :authorize_read_build!
+  before_action :validate_artifacts!
 
   def download
     unless artifacts_file.file_storage?
       return redirect_to artifacts_file.url
     end
 
-    unless artifacts_file.exists?
-      return render_404
-    end
-
     send_file artifacts_file.path, disposition: 'attachment'
   end
 
   def browse
-    return render_404 unless build.artifacts?
-
     directory = params[:path] ? "#{params[:path]}/" : ''
     @entry = build.artifacts_metadata_entry(directory)
 
@@ -41,6 +36,10 @@ class Projects::ArtifactsController < Projects::ApplicationController
 
   private
 
+  def validate_artifacts!
+    render_404 unless build.artifacts?
+  end
+
   def build
     @build ||= project.builds.find_by!(id: params[:build_id])
   end