Drive Unmount Issue

[yofukashino]

Description
While using this extension, I have the wallpaper on a secondary drive.
So, when I shut down for 2 seconds there it gives an error about failing to unmount the drive. Then shuts down or reboots.

Seems like the issue is with the extension not releasing the file, or at least not at the time for a second or two.

OS and Shell Information
Please provide your OS name and version, GNOME Shell version, and the session type (X11/Wayland).

• OS: Arch Linux
• GNOME Shell: 48
• Session type: Wayland (Tested on Xorg too)

Steps to Reproduce
Please provide the steps to reproduce the bug you are encountering.

1. Have Fstab mount the secondary drive for you.
2. Put wallpaper on it, and use it.
3. Reboot

Expected Behavior
No Error about failing to unmount the drive

Actual Behavior
Error about failing to unmount the drive for 2 seconds

Additional Information
Please provide any additional information that you think might be helpful, such as error messages, screenshots, screen recordings, or links.