1. Install an icon pack.
2. Open settings and select the icon pack.
3. Go back to the home screen to check out the icons.
4. Decide you don't like the icon pack and uninstall it.
5. Notice that the icons haven't reset to stock.
6. Open the settings and press the button for selecting an icon pack.
It'll force close Action Launcher and will now force close every time you try step 6 again.
7. Reinstall the icon pack.
8. Repeat step 6 - it'll force close again.
9. Repeat step 6 again - should open up and let you select stock.
10. Uninstall the icon pack again.