fix: prevent StateError crash in getTriggeredAlarm lookup (#906)

[Varvyju]

Summary

Fixes Issue #906.

Prevents a fatal StateError crash when getTriggeredAlarm is called and no enabled alarms match the current time.

Changes Made

• ISAR Provider: Replaced the unoptimized .findAll() query with .findFirst() for better memory and IO performance. Added a null-safety guard to return null gracefully instead of throwing a StateError.
• Firestore Provider: Applied the same empty-result guard, adding .limit(1) to optimize the document read query, and properly returning null if the snapshot is empty.
• Scope: Unlike previous attempts at this issue (e.g., PR fix: handle empty triggered alarm lookup #907), this fix is strictly scoped to the database queries, handles both ISAR and Firestore parity, and does not introduce unrelated UI changes.

Testing Done

• Verified flutter analyze passes with no errors.
• Confirmed that empty query results now resolve safely without crashing the background service.

[Copilot]

Pull request overview

Fixes a crash in triggered-alarm lookup by making both ISAR and Firestore implementations return null when no enabled alarm matches the requested time, and by reducing query overhead.

Changes:

• ISAR: switch from findAll() to findFirst() and return null instead of throwing on empty results.
• Firestore: add limit(1), guard empty snapshots, and return null instead of indexing into an empty list.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 7 comments.

File	Description
lib/app/data/providers/isar_provider.dart	Makes triggered-alarm query nullable and more efficient via findFirst() + empty-result guard.
lib/app/data/providers/firestore_provider.dart	Adds empty-result guard and query optimization via limit(1), returning nullable results.

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[Copilot]

Logging a debugPrint every time no alarm matches can get noisy if this lookup runs frequently (e.g., background polling). Consider either removing this log, downgrading it behind a debug flag, or rate-limiting it to avoid log spam in normal operation.

Suggested change

	debugPrint('No enabled alarm found in ISAR for time: $time');
	if (kDebugMode) {
	debugPrint('No enabled alarm found in ISAR for time: $time');
	}

[Copilot]

The previous implementation of getTriggeredAlarm is left in the file as commented-out code. Since it’s already available in git history, please remove the dead commented-out block to reduce clutter and avoid future confusion.

Suggested change

	// static Future<AlarmModel> getTriggeredAlarm(String time) async {
	// final isarProvider = IsarDb();
	// final db = await isarProvider.db;
	// final alarms = await db.alarmModels
	// .where()
	// .filter()
	// .isEnabledEqualTo(true)
	// .and()
	// .alarmTimeEqualTo(time)
	// .findAll();
	// return alarms.first;
	// }

[Copilot]

getTriggeredAlarm is not indented consistently with the rest of the IsarDb class (it starts at column 0). Please run dart format / adjust indentation so the method aligns with surrounding static methods, improving readability and keeping style consistent.

Suggested change

	static Future<AlarmModel?> getTriggeredAlarm(String time) async {
	final isarProvider = IsarDb();
	final db = await isarProvider.db;
	// Use findFirst() instead of findAll() to save memory and IO
	final alarm = await db.alarmModels
	.where()
	.filter()
	.isEnabledEqualTo(true)
	.and()
	.alarmTimeEqualTo(time)
	.findFirst();
	if (alarm == null) {
	debugPrint('No enabled alarm found in ISAR for time: $time');
	return null; // Return null instead of throwing an error to prevent crashes
	}
	return alarm;
	}
	static Future<AlarmModel?> getTriggeredAlarm(String time) async {
	final isarProvider = IsarDb();
	final db = await isarProvider.db;
	// Use findFirst() instead of findAll() to save memory and IO
	final alarm = await db.alarmModels
	.where()
	.filter()
	.isEnabledEqualTo(true)
	.and()
	.alarmTimeEqualTo(time)
	.findFirst();
	if (alarm == null) {
	debugPrint('No enabled alarm found in ISAR for time: $time');
	return null; // Return null instead of throwing an error to prevent crashes
	}
	return alarm;
	}

[Copilot]

Logging a debugPrint every time no alarm matches can get noisy if this lookup runs frequently (e.g., background polling). Consider removing this log, guarding it behind a debug-only flag, or rate-limiting it to avoid log spam in normal operation.

Suggested change

	debugPrint('No enabled alarm found in ISAR for time: $time');
	assert(() {
	debugPrint('No enabled alarm found in ISAR for time: $time');
	return true;
	}());

[Copilot]

The previous getTriggeredAlarm implementation is kept as commented-out code. Please remove the dead commented-out block (git history preserves it) to reduce noise and maintenance overhead.

Suggested change

	// static Future<AlarmModel> getTriggeredAlarm(
	// UserModel? user,
	// String time,
	// ) async {
	// HomeController homeController = Get.find<HomeController>();
	// if (user == null) return homeController.genFakeAlarmModel();
	// QuerySnapshot snapshot = await _alarmsCollection(user)
	// .where('isEnabled', isEqualTo: true)
	// .where('alarmTime', isEqualTo: time)
	// .get();
	// List list = snapshot.docs.map((DocumentSnapshot document) {
	// return AlarmModel.fromDocumentSnapshot(
	// documentSnapshot: document,
	// user: user,
	// );
	// }).toList();
	// return list[0];

[Copilot]

This change removes the prior user == null guard (it used to return a fake model). As written, the method will query _alarmsCollection(null) (which points at the top-level alarms collection) and then build an AlarmModel with user: null. Please add an explicit user == null early return (likely null) to avoid unintended/unauthorized reads and to keep null-user behavior consistent with other methods in this provider (e.g., getLatestAlarm, getAlarm, addAlarm).

[Copilot]

Catching a broad catch (e) and returning null will also swallow unexpected non-Firestore errors (e.g., mapping/logic bugs), making defects harder to detect. Consider catching FirebaseException (or a narrower set of expected exceptions) and rethrowing unexpected exceptions after logging so real errors aren’t silently masked.

Suggested change

	} catch (e) {
	debugPrint('Error fetching triggered alarm from Firestore: $e');
	return null;
	} on FirebaseException catch (e) {
	debugPrint('Error fetching triggered alarm from Firestore: $e');
	return null;
	} catch (e, stackTrace) {
	debugPrint('Unexpected error fetching triggered alarm from Firestore: $e');
	debugPrint('Stack trace: $stackTrace');
	rethrow;