readability refactor of rule deletion from escalation policies when n…

…eeded

pagerduty/resource_pagerduty_schedule.go

@@ -621,16 +621,23 @@ func removeScheduleFromEP(c *pagerduty.Client, scheduleID string, ep *pagerduty.
 	epr := ep.EscalationRules
 	for ri, r := range epr {
 		for index, target := range r.Targets {
-			if target.Type == "schedule_reference" && target.ID == scheduleID {
-				// Remove Schedule as a configured Target from the Escalation Rules
-				// slice
-				r.Targets = append(r.Targets[:index], r.Targets[index+1:]...)
+			isScheduleConfiguredInEscalationRule := target.Type == "schedule_reference" && target.ID == scheduleID
+			if !isScheduleConfiguredInEscalationRule {
+				continue
+			}
+
+			if isScheduleConfiguredInEscalationRule {
+				if len(r.Targets) > 1 {
+					// Removing Schedule as a configured Target from the Escalation Rules
+					// slice.
+					r.Targets = append(r.Targets[:index], r.Targets[index+1:]...)
+				} else {
+					// Removing Escalation Rules that will end up having no target configured.
+					epr = append(epr[:ri], epr[ri+1:]...)
+				}
 				needsToUpdate = true
 			}
 		}
-		if len(r.Targets) == 0 {
-			epr = append(epr[:ri], epr[ri+1:]...)
-		}
 	}
 	if !needsToUpdate {
 		return nil