Element Desktop went blank while reading rooms

### Steps to reproduce

Cannot reliably reproduce, but it does happen now-and-then

### Outcome

#### What did you expect?

Not a white screen

#### What happened instead?

I was reading rooms using Shift+Alt+Arrows and Element suddenly went all white. It came back a second after I pressed Ctrl+Shift+I to open the dev console to rageshake.

I have also seen this a few times in the past but can't remember what I was doing then.


This issue has also been reported by a customer.

Their report:

> I'm seeing this "Message search initialisation failed" error on my Element Desktop client that's logged into our test on-prem server.
>
> That blank screen instance happened when I tried editing my "Also, I'm seeing..." message above and clicking save. This is on Windows 10. My versions are: Element version: 1.11.86 Crypto version: Rust SDK 0.7.2 (517d99b), Vodozemac 0.7.0
>
> A CTRL-SHIFT-R didn't do anything in the window. I had to quit the client and relaunch.

### Operating system

Debian 12

### Application version

Element version: 1.11.87 Crypto version: Rust SDK 0.7.2 (517d99b), Vodozemac 0.7.0

### How did you install the app?

Element Debian APT repo

### Homeserver

element.io Synapse 1.120.2

### Will you send logs?

Yes

No source file or test is identified. Start by reproducing the Shift+Alt+Arrows navigation on Debian 12 with Element 1.11.87 and inspect the Ctrl+Shift+I console for the reported “Message search initialisation failed” error; done means the blank-screen cause is identified, fixed, and regression-tested.

Written by the indexing model from the issue text.