fix single mode & improve invalid path handling

[CITIZENDOT]

Summary

Fixes single play mode. And handles invalid paths cleanly

References

closes #insert number here

Explanation

🤖 Generated by Copilot at c8f1fac

• Added getNextTrack function to determine the next track to play based on the media resources, the current track, and the play mode (link, link)
• Modified updateMediaElement function to use getNextTrack function and handle different play modes consistently (link, link)
• Modified updateMediaElement function to set the media.ended and media.track values before loading the media element (link)
• Modified updateMediaElement function to set the media.ended and media.waiting values in case of an error while loading the media element (link)
• Modified MediaReactor function to update the media element whenever the media.playMode value changes (link)

🤖 Generated by Copilot at c8f1fac

updateMediaElement with the power of sound
getNextTrack from the resources we found
Choose your play mode, single, loop, or shuffle
Control your destiny, don't let them muffle

QA Steps

List any additional steps required to QA the changes of this PR, as well as any supplemental images or videos.

Checklist

• If this PR is still a WIP, convert to a draft
• When this PR is ready, mark it as "Ready for review"
• ensure all checks pass
• Changes have been manually QA'd
• Changes reviewed by at least 2 approved reviewers