Crashing very often (every few minutes)

### Steps to reproduce

App is crashing on random occassions.

### Outcome

It's crashing every few minutes. I couldn't figure out why. Sometimes it crashed immediately after sending a message. It often crashes while scrolling back in timeline. However, often it happens randomly, for example, while in a call, and there is no activity in the app (no new messages received or sent), but it happens after a much longer time interval than when I use the app.

I sent numerous crash reports using the in-app crash reporting feature. Every time it displayed the "Do you send crash reports?" dialog, I clicked yes. This demostrates how often this happens.

Do you see these crash reports?

### Your phone model

Sent using in-app crash report feature.

### Operating system version

Sent using in-app crash report feature.

### Application version and app store

1.4.2, but it happens since 1.4.0 (or maybe even in 1.3.18)

### Homeserver

Sent using in-app crash report feature.

### Will you send logs?

I have already sent many, and will send more.