Empty tab slot left behind after deleting Session

[philrz]

Repro is with Zui commit d3a0402. This was first spotted when testing the #3132 branch but we decided to merge what was there and fix this after.

Repro steps shown in the attached video:

1. Load some data
2. Click to the Sessions list in the left panel
3. Close the pool page for the data just added
4. Start one Session and run a count() on the pool
5. Start a second session and run a search (e.g., google) on the pool
6. Right-click and delete the Session with count() from the list

An empty slot is left behind for the deleted tab. This empty slot is filled in as soon as I click another tab.

Repro.mp4

[philrz]

Verified in Zui commit f6f28ac.

As shown in the attached video, now when I repeat the repro steps, there's no longer an empty tab slot left behind after I delete the Session.

Verify.mp4

Thanks @jameskerr!