[BUG] CameraView: Rapidly capturing a picture throws an uncatchable exception (Windows, iOS)

[tschbc]

Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

After waiting for Camera.StartCameraPreview to complete, taking pictures rapidly throws an uncatchable exception, crashing the app.

On Windows it's not as bad: you need to double-click a shutter button soon after the camera preview becomes active. If you single click, then wait a few seconds, no amount of rapid clicking will crash the app.

On iOS, you can consistently crash the app by double-tapping a shutter button at any point after the preview becomes active.

Edit: it looks like the ValueTask returned from Camera.StartCameraPreview never completes, execution stays halted. The first Camera.CaptureImage call throws a TaskCanceledException from Camera.StartCameraPreview that breaks out. If you only capture one image, wait about 4-ish seconds and capture more images, no more TaskCanceledExceptions are thrown (on Windows at least).

Expected Behavior

Throw an exception that can be caught—or some other ideal error state that is feasible.

Steps To Reproduce

1. Run solution from repro repo
2. Windows: double-click the "Take photo" button soon after the camera preview is active
3. Observe uncatchable exception and crash.
4. iOS: at any point after the camera preview has loaded, double-tap the "Take photo" button
5. Observe uncatchable exception and crash.

Link to public reproduction project repository

https://github.com/tschbc/CmtyToolkitCameraViewIssues

Environment

- .NET MAUI CommunityToolkit: 9.0.3
- OS: Windows 10 19045.4780
- OS: iOS 17.6.1
- .NET MAUI: 8.0.90

Anything else?

No response