fix: http 500 on user creation page

there's a lesson about being more careful with non-null assertion in there somewhere

src/routes/dash/users/[id]/+page.server.ts

@@ -17,7 +17,7 @@ export const load: ServerLoad = async ({ locals: { guard }, params }) => {
   }
 
   return {
-    user: toPublicUser(user!),
+    user: user ? toPublicUser(user) : undefined,
     groups: await groups.getAll(),
     devices: await devices.getAll(),
   };