If you cancel action in a delete event when deleting language branch, UI hangs

Description

Steps to reproduce:
1) Create an Alloy project.
2) Install the EPiServer.Labs.LanguageManager plugin.
3) Add the code in the attached EventInitialization.cs.txt file.
4) Run the site.
5) Add the LanguageManager gadget.
6) Select any page and create a version in another language so it has at least 2 languages.
7) Use the LanguageManager gadget to delete the newly created language branch.

Expected result:
A dialog displaying a cancelation reason.

Actual result:
The ui fades to gray, a spinner spins forever, and you see this get error "Error: Unable to load /EPiServer/EPiServer.Labs.LanguageManager/Stores/language/ status: 500"