BUG/MINOR: checks: queues null-deref

queues can be null if calloc() failed.
Bypass free* calls when calloc did fail.
diff --git a/src/checks.c b/src/checks.c
index 52c762b..5772c4f 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -3235,7 +3235,7 @@
 
 	if ((queues = calloc(mls->count, sizeof(*queues))) == NULL) {
 		memprintf(err, "out of memory while allocating mailer alerts queues");
-		goto error;
+		goto fail_no_queue;
 	}
 
 	for (mailer = mls->mailer_list; mailer; i++, mailer = mailer->next) {
@@ -3292,6 +3292,7 @@
 		free_check(check);
 	}
 	free(queues);
+  fail_no_queue:
 	return 1;
 }