                         else null
                     when "assigned_to"
                         if value
-                            return scope.constants.users[value].full_name
+                            try
+                                return scope.constants.users[value].full_name
+                            catch
+                                return null
                         return $i18next.t("common.unassigned")
                     when "is_blocked"
                         if value is true

                        else null
                    when "watchers"
                        if value
                            return _.map(value, (v) -> scope.constants.users[v].full_name).join(", ")
                        return null
                    else value
            task: (name, value) ->

                        else null
                    when "watchers"
                        if value
                            watchers_ids = _.map(value, (v) -> parseInt(v, 10))
                            watchers = _.findByValues(scope.constants.users, "id", watchers_ids)
                            return _.map(watchers, "full_name").join(", ")
                        return null
                    else value
            issue: (name, value) ->
                return switch name
                    when "type"
                        if value
                            try
                                return scope.constants.issueTypes[value].name
                            catch
                                return null
                        return null
                    when "priority"
                        if value
                            try
                                return scope.constants.priorities[value].name
                            catch
                                return null
                        return null
                    when "status"
                        if value
                            try
                                return scope.constants.issueStatuses[value].name
                            catch
                                return null
                        return null
                    when "severity"
                        if value
                            try
                                return scope.constants.severities[value].name
                            catch
                                return null
                        return null
                    when "tags"
                        if value
