Build:
Stage

Affected platforms:
Windows 10 64-bit

Browsers tested on:
Firefox

Preconditions:
Latest version of Relay addon is installed.

Steps to reproduce:

1. Navigate to Stage server and log in to Firefox Relay.
2. Create some aliases from dashboard and generate some from other websites (facebook, reddit).
3. Disable an alias.
4. Go back to Reddit page, refresh it and open the context menu.
5. Click Firefox Relay to see the submenus and look in each of them.
6. Enable the alias.
7. Repeat steps 4 and 5.
8. Delete aliases.
9. Repeat steps 4 and 5.

Actual result:
Firefox browser crashes.

Expected result:
Firefox browser doesn't crash.

Note:
Was not able to figure out some clear steps for this issue. It is not always reproducible but I was able to reproduce it a few times.
I played a lot with the aliases and looked in the context menu for facebook and reddit and at some point when I got to reddit and clicked Firefox Relay in the menu it crashed.