if curIdx := getRIndex(sorted, c.name); curIdx == -1 {
					// if before callback already sorted, append current callback just after it
					sorted = append(sorted[:sortedIdx], append([]string{c.name}, sorted[sortedIdx:]...)...)
				} else if curIdx > sortedIdx {
					return fmt.Errorf("conflicting callback %s with before %s", c.name, c.before)
				}
			} else if idx := getRIndex(names, c.before); idx != -1 {
				// if before callback exists