From 147410df77c0919ffa29f8778871eeedffc6cd3b Mon Sep 17 00:00:00 2001
From: Leo Jeong <80350771+33tm@users.noreply.github.com>
Date: Thu, 22 Aug 2024 13:18:59 -0700
Subject: [PATCH] account for null alternate

---
 shared/util/schedule.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/shared/util/schedule.ts b/shared/util/schedule.ts
index 515c903..522117f 100644
--- a/shared/util/schedule.ts
+++ b/shared/util/schedule.ts
@@ -8,8 +8,9 @@ import schedule, {SCHOOL_START, SCHOOL_END, SCHOOL_END_EXCLUSIVE, PeriodObj} fro
 export const numToWeekday = (num: number) => ['S', 'M', 'T', 'W', 'R', 'F', 'A'][num];
 
 // Account for how the weekly SELF/SH rotation aren't necessarily alternates
-export function isAlternate(normal: PeriodObj[], alternate: PeriodObj[]) {
-    const selfShFilter = ({ n }) => !['S', 'H'].includes(n);
+export function isAlternate(normal: PeriodObj[], alternate: PeriodObj[] | null) {
+    if (!alternate) return true
+    const selfShFilter = ({ n }: { n: PeriodObj["n"] }) => !['S', 'H'].includes(n);
     return JSON.stringify(normal.filter(selfShFilter)) !== JSON.stringify(alternate.filter(selfShFilter));
 }