Fix [skip ci]

app/models/research/hal.rb

@@ -28,7 +28,7 @@ module Research::Hal
   def self.clear_queue!
     ids = []
     Delayed::Job.find_each do |job|
-      if  job.payload_object.method_name == :sync_indirect_object_with_git_without_delay &&
+      if  job.payload_object&.method_name == :sync_indirect_object_with_git_without_delay &&
           job.payload_object.args.first.is_a?(Research::Hal::Publication)
         ids << job.id
       end