Closing a window before STG finished loading (can take 3 seconds) causes an error

[tuxayo]

Describe the bug
Title ^_^

To Reproduce
Steps to reproduce the behavior:

1. Open a blank new window or a link in a new window
2. see that STG is loading
3. close the window before it finished
4. See error

Expected behavior
It should not trigger an error. On my machine it usually takes 2 seconds to have STG load on a new window. Sometimes more. And when I open a new window by mistake, or change my mind or see very quickly what I wanted to check on a page, I close it and it triggers an error.

Desktop (please complete the following information):

• OS and version: EndeavourOS (based on Arch Linux)
• Firefox version: dev edition 116.0b8 , happens since many months.
• Simple Tab Groups version: 5.2, happens since many months.

Additional context
Thanks for making STG <3

[zkhcohen]

Related to: #1035