fix: replace non-growable List.empty() with [] literal to prevent Uns…

[vibhutomer]

Description

This PR resolves a hidden runtime crash risk caused by the default behavior of Dart's List.empty().

In several service implementations, List.empty() was used to initialize lists or as a fallback return value in catch blocks. Because List.empty() defaults to growable: false, any subsequent attempt by the UI or providers to append items (.add()) to these fallback lists would result in an immediate UnsupportedError (Cannot add to a fixed-length list).

Changes Made

• Replaced instances of List.empty() with the standard growable list literal [] in biometrics_service_impl.dart and process_spec_service_impl.dart.
• This ensures that fallback lists returned during network or platform failures can be safely interacted with by the UI without throwing exceptions.

Related Issue

Closes #1049

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Stability improvement (prevents runtime collection errors)

Checklist

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• My changes generate no new warnings or exceptions.

Summary by CodeRabbit

• Refactor
  • Internal code optimizations for improved consistency across the codebase. No user-facing changes.

[coderabbitai]

Walkthrough

This PR replaces fixed-length List.empty() initializations with growable list literals ([]) across two Android platform service implementations (BiometricsServiceImpl and ProcessSpecServiceImpl). This prevents UnsupportedError crashes when consuming UI code attempts to add items to these fallback empty lists after API failures.

Changes

List Initialization Safety

Layer / File(s)	Summary
BiometricsServiceImpl device list initialization lib/platform_android/biometrics_service_impl.dart	getListOfDevices initializes deviceList using growable [] instead of fixed-length List.empty().
ProcessSpecServiceImpl fallback list initializations lib/platform_android/process_spec_service_impl.dart	getNewProcessSpec, getOptionalLanguageCodes, and getSettingSpec replace List.empty() with growable [] in error handling and fallback paths.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 Lists that couldn't grow were causing strife,
With crashes when you tried to add new life,
But [] brings flexibility and grace,
Now empty fallbacks find their proper place!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title clearly and specifically describes the main change: replacing non-growable List.empty() with [] literals to prevent UnsupportedError.
Linked Issues check	✅ Passed	The PR changes in biometrics_service_impl.dart and process_spec_service_impl.dart directly address issue #1049 by replacing List.empty() with [] in fallback error handling paths.
Out of Scope Changes check	✅ Passed	All changes are directly related to replacing List.empty() with [] in the two specified files; no unrelated modifications detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@lib/platform_android/process_spec_service_impl.dart`:
- Around line 21-23: getMandatoryLanguageCodes() still returns a fixed-length
empty list via List.empty() in its exception/fallback paths which causes
UnsupportedError when callers try to mutate it; replace those List.empty()
returns with a growable list (e.g., use [] or List.empty(growable: true) or
List.from([])) in the exception branches inside getMandatoryLanguageCodes() so
callers can safely modify the fallback list.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: d51602cc-867c-4a82-a893-abe3cc0c5169

📥 Commits

Reviewing files that changed from the base of the PR and between aef4fb6 and 945298f.

📒 Files selected for processing (2)

• lib/platform_android/biometrics_service_impl.dart
• lib/platform_android/process_spec_service_impl.dart

[coderabbitai]

⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Fix is still partial: one fallback path remains fixed-length.

getMandatoryLanguageCodes() still uses List.empty() in exception paths (Line 61, Line 63), so the same UnsupportedError can still occur when consumers mutate the returned fallback list.

Suggested patch

   Future<List<String?>> getMandatoryLanguageCodes() async {
     List<String?> mandatoryLanguageCodes;
     try {
       mandatoryLanguageCodes = await ProcessSpecApi().getMandatoryLanguageCodes();
     } on PlatformException {
       debugPrint("Process Spec Api failed!");
-      mandatoryLanguageCodes = List.empty();
+      mandatoryLanguageCodes = [];
     }  catch (e) {
-      mandatoryLanguageCodes = List.empty();
+      mandatoryLanguageCodes = [];
       debugPrint("Process spec fetch error: $e");
     }
     return mandatoryLanguageCodes;
   }

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/platform_android/process_spec_service_impl.dart` around lines 21 - 23,
getMandatoryLanguageCodes() still returns a fixed-length empty list via
List.empty() in its exception/fallback paths which causes UnsupportedError when
callers try to mutate it; replace those List.empty() returns with a growable
list (e.g., use [] or List.empty(growable: true) or List.from([])) in the
exception branches inside getMandatoryLanguageCodes() so callers can safely
modify the fallback list.