[Bug] "Failed to save frame" when using Shift + S

[DereC4]

Description:
When attempting to save a frame using the keyboard shortcut (Shift + S) in Screenbox, the application fails to save the image and displays a toast error message indicating a null reference exception.

Steps to Reproduce:

• Open a video file in Screenbox.
• Play or scrub to any frame in the video.
• Press the Shift + S shortcut to trigger the "save frame" functionality.

Expected Behavior:
Screenbox should successfully capture and save the current video frame to the designated directory without throwing an error.

Actual Behavior:
No frame is saved. A red error toast appears at the bottom of the screen with the message:
Failed to save frame Object reference not set to an instance of an object.

[dosubot]

Hi @DereC4! I'm Dosu and I’m helping the Screenbox team.

This is a known bug that has been reported by other users across versions 0.15.1.0 [1] and 0.16.0.0 [2]. The NullReferenceException occurs in SaveSnapshotInternalAsync in PlayerControlsViewModel.cs, likely because _mediaPlayer is either null or not properly initialized as a VlcMediaPlayer instance when the snapshot is attempted.

The error handling around this was refactored in PR #794, which improved how the error is communicated to the user, but the underlying root cause — the media player not being properly available when the shortcut is triggered — may not have been fully addressed.

For context, a related but separate issue was also reported where saving frames near the end of a video produces a "Value does not fall within the expected range" error [3].

To reply, just mention @dosu.

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