Crash - NSScreen.screens array accessed without bounds check

[ebrindley]

Crash - NSScreen.screens array accessed without bounds check

Labels: bug, crash, low-priority

Description

NotificationManager accesses NSScreen.screens[0] as a fallback without checking if the array is empty, which crashes in headless mode or when all screens are disconnected.

User Impact

• Crash if app runs in headless mode or when all screens disconnected

• Edge case but can occur in server environments or during screen configuration changes

• Affects users with unusual multi-monitor setups during transitions

Technical Details

File: VoiceInk/Notifications/NotificationManager.swift

Line: 83

let activeScreen = NSApp.keyWindow?.screen ?? NSScreen.main ?? NSScreen.screens[0]

The method is correctly marked @MainActor (line 81), so thread safety is not an issue. The problem is the array subscript on NSScreen.screens[0] which will crash if no screens are available.

Reproduction

1. Run app in headless mode (no display connected)

2. Trigger a notification

3. Observe crash on array access

Recommended Fix

Replace line 83 in VoiceInk/Notifications/NotificationManager.swift:

let activeScreen: NSScreen

if let windowScreen = NSApp.keyWindow?.screen {

    activeScreen = windowScreen

} else if let mainScreen = NSScreen.main {

    activeScreen = mainScreen

} else if let firstScreen = NSScreen.screens.first {

    activeScreen = firstScreen

} else {

    // No screens available - cannot position notification

    return

}

Testing

1. Test with multiple monitors

2. Test connecting/disconnecting displays during app usage

3. Verify notifications appear correctly in all scenarios

4. Test in VM or headless environment if possible