Removing the last item from the play queue results in Javascript error.

[Nocifer]

Describe the bug
When you try to remove the last item from the play queue, the following error is printed:

To Reproduce
Steps to reproduce the behavior:

1. Add one or more tracks to the play queue.
2. Select them all, right click on them and choose "Remove selected"; or select them all but one and remove them, and then select the last remaining track and try to remove it by its lonesome; i.e. it makes no difference whether it's single or batch removal performed.

Expected behavior
Tracks should be removed cleanly.

Desktop (please complete the following information):

• OS: Arch Linux
• Version 0.13.1

[jeffvli]

Thanks for reporting, fixed!