Retry file conversion in case of DB connection issues

Fix CODEOCEAN-RZ

app/controllers/concerns/file_conversion.rb

@@ -4,6 +4,7 @@ module FileConversion
   private
 
   def convert_files_json_to_files(files_json)
+    retry_block do
       # Return an empty list of files and directories if the files_json is nil
       return [[], []] if files_json.blank?
 
@@ -38,8 +39,18 @@ module FileConversion
       end
       [augment_files_for_download(files), directories]
     end
+  end
 
   def augment_files_for_download(files)
     raise NotImplementedError
   end
+
+  def retry_block(count: 1)
+    yield
+  rescue ActiveRecord::StatementInvalid => e
+    count -= 1
+    retry if count.positive?
+
+    raise e
+  end
 end