[Intermittent] Mozilla VPN is crashing after swipe-killing the app while the VPN is ON

[data-sync-user]

Version/build found in:

• 2.21.0 (2.202403072206);

Reproducible on:

• iOS 17.3.1;

Prerequisites:

• Have the Mozilla VPN app installed and opened;
• Have a Mozilla account with an active subscription;
• Be signed in; 

Steps to reproduce:

1. Turn the VPN ON
2. Wait for about 1-2 minutes, then swipe-kill the app.
3. Reopen the app.

Expected result:

• The activation screen is displayed.

Actual result:

• The app is crashing. The crash report screen was not displayed - only the modal from the OS.

Notes:

• See attached logs;

┆Issue is synchronized with this Jira Bug ┆Reporter: Raluca Monica Ilban