} else if curIdx < sortedIdx {
					return fmt.Errorf("conflicting callback %s with before %s", c.name, c.after)
				}
			} else if idx := getRIndex(names, c.after); idx != -1 {
				// if after callback exists but haven't sorted
				// set after callback's before callback to current callback
				after := cs[idx]

				if after.before == "" {
					after.before = c.name
				}

				if err := sortCallback(after); err != nil {