main: Fix assignment to nil map

main.go

@@ -66,7 +66,7 @@ func (s *solver) CleanUp(ch *whapi.ChallengeRequest) error {
 	}
 
 	var lastErr error
-	var zones map[int]interface{}
+	zones := map[int]interface{}{}
 	for _, r := range records {
 		if r.Type != "txt_record" {
 			continue