From 4063b4f597fcb54e09276ab654bfdce6d6bd789b Mon Sep 17 00:00:00 2001
From: Arsalan Sufi <arsalan@voting.works>
Date: Thu, 5 Oct 2023 22:47:46 -0400
Subject: [PATCH] Make sure saving backup on VxCentralScan doesn't crash app
 when no USB

Also clear error message on subsequent backup attempts
---
 .../frontend/src/screens/admin_actions_screen.tsx            | 1 +
 libs/backend/src/cast_vote_records/export.ts                 | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/apps/central-scan/frontend/src/screens/admin_actions_screen.tsx b/apps/central-scan/frontend/src/screens/admin_actions_screen.tsx
index 9c2c19a694b..c8b35b3301e 100644
--- a/apps/central-scan/frontend/src/screens/admin_actions_screen.tsx
+++ b/apps/central-scan/frontend/src/screens/admin_actions_screen.tsx
@@ -96,6 +96,7 @@ export function AdminActionsScreen({
 
   function saveBackup() {
     setIsBackingUp(true);
+    setBackupError('');
     exportCastVoteRecordsToUsbDriveMutation.mutate(
       { isMinimalExport: false },
       {
diff --git a/libs/backend/src/cast_vote_records/export.ts b/libs/backend/src/cast_vote_records/export.ts
index 08e3cece62d..96e5902d706 100644
--- a/libs/backend/src/cast_vote_records/export.ts
+++ b/libs/backend/src/cast_vote_records/export.ts
@@ -13,6 +13,7 @@ import {
 import {
   assert,
   assertDefined,
+  err,
   ok,
   Result,
   throwIllegalValue,
@@ -673,7 +674,9 @@ export async function exportCastVoteRecordsToUsbDrive(
         ? usbDriveStatus.mountPoint
         : undefined;
   }
-  assert(usbMountPoint !== undefined);
+  if (usbMountPoint === undefined) {
+    return err({ type: 'missing-usb-drive' });
+  }
   const exportContext: ExportContext = {
     exporter: new Exporter({
       allowedExportPatterns: SCAN_ALLOWED_EXPORT_PATTERNS,