Firefox closes when the close window button is clicked

[Klawz312]

Describe the bug
Clicking the close window button in Container Tab Groups panel closes Firefox instead of the sidebar.

To Reproduce
Steps to reproduce the behavior:

1. Open Container Tab Groups in the sidebar
2. Click on 'Close Window' button (x in the upper right corner of the sidebar)
3. Firefox closes and needs to be restarted again.

Expected behavior
The sidebar should close. Firefox should stay open.

Screenshots

Console outputs

[background/background-install-handler] onInstalled: 11.11.0.200 -> 11.11.0.200 background.6d6ff02f.js:380:677
[background/background-tab-lifecycle] appearance.popupSize changed: standard background.6d6ff02f.js:380:677
[background/ActiveContainerService] ActiveContainerService.setActiveContainer: windowId = 66 cookieStoreId = firefox-default background.6d6ff02f.js:380:677
[background/ContainerTabOpenerService] open_new_tab_in_container: cookieStoreId=firefox-container-53 background.6d6ff02f.js:380:677
Error: Invalid tab ID: 14 background.e90f4d8b.js:409:1124
[background/ContainerTabOpenerService] open_new_tab_in_container: cookieStoreId=firefox-container-53 background.6d6ff02f.js:380:677
Error: Invalid tab ID: 16 background.e90f4d8b.js:409:1124
[background/ContainerTabOpenerService] open_new_tab_in_container: cookieStoreId=firefox-container-53 background.6d6ff02f.js:380:677
[popup-v2/BrowserStateStore] Error: Invalid tab ID: 19 background.6d6ff02f.js:380:740
Error: Invalid tab ID: 19 background.e90f4d8b.js:409:1124
[background/ContainerTabOpenerService] open_new_tab_in_container: cookieStoreId=firefox-container-53 background.6d6ff02f.js:380:677
[popup-v2/BrowserStateStore] Error: Invalid tab ID: 22 background.6d6ff02f.js:380:740
Error: Invalid tab ID: 22 background.e90f4d8b.js:409:1124
[background/background-container-observer] contextualIdentity tmp-53 (firefox-container-53) removed background.6d6ff02f.js:380:677
[background/TemporaryContainerService] Removed temporary container firefox-container-53 background.6d6ff02f.js:380:677

If you cannot find any errors there, try opening the browser console (hamburger menu > more tools > browser console).

Firefox (please complete the following information):

• OS: Windows 10 Home Edition 22H2 Build 19045
• Browser edition and version: Firefox stable 136.0.1
• Extension version: 11.11.0.200

Additional context
I thought this happened when you opened a temporary tab first but instead it will happen when you click the 'Close Window' button in the sidebar panel when Container Tab Groups is open.

This may be intended behavior but I would expect to see the dialog to ask if I want to close the browser window like when I close the browser by clicking the red x in the upper right corner of the browser window.

[metastable-void]

Since this can lead to loss of open tabs, I'll try to fix this with a raised priority.