Browser crash when trying to close tab with sidebar open

[srirambv]

Description

IMPORTANT: Your crash has already been automatically reported to our crash system. Please file this bug only if you can provide more information about it.

Brave Version: 1.70.115 Chromium: 129.0.6668.59
Operating System: Windows NT 10.0.22631

URL (if applicable) where crash occurred:

Can you reproduce this crash?
Yes

What steps will reproduce this crash? (If it's not reproducible, what were you doing just before the crash?)

1. Launch browser with Leo pointing to staging
2. Connect to staging account and load Leo credentials
3. Open a new tab and load Leo in sidebar
4. Navigate back and forth between two tabs where Leo is opened in both
5. Close one of the tab
6. Browser crashes

DO NOT CHANGE BELOW THIS LINE
Crash ID: crash/ead61900-9ce4-970c-0000-000000000000
Crash ID: crash/e7d61900-9ce4-970c-0000-000000000000

cc: @brave/qa-team @iefremov @rebron