Crash when trying to leave room

### Steps to reproduce

The application crash when trying to leave room from the 2 following screens:
- the quick action menu in members list
- the leave button on member info sheet from room members list

This happens because of `lastAdmin` test added recently.

Fix on Tchap side can be found here: https://github.com/tchapgouv/tchap-ios/pull/1237

### Outcome

#### What did you expect?

#### What happened instead?

### Your phone model

any iPhone

### Operating system version

iOS 18 or iOS 26

### Application version

Element Classic 1.11.32

### Homeserver

_No response_

### Will you send logs?

No