Having space in homeserver FQDN kills the Android app

### Steps to reproduce

Entering space after homeserver URL, e.g. "matrix.org " kills the Android app (tested on 1.5.7).

My keyboard auto-completed my homeserver URL, but added a space character at the end inadvertently.

The app instantly crashed. There wasn't even a single HTTP request to homeserver.

### Outcome

#### What did you expect?
The app doesn't crash. It either ignores the space (preferable) or notifies the user of error (less preferable)

#### What happened instead?
The app instantly crashed. Not even a single HTTP request was sent to the homeserver

### Your phone model

LG V30+ (LG-H930DS)

### Operating system version

9

### Application version and app store

Element 1.5.7 (olm 3.2.12) from Google Play Store

### Homeserver

Non-public, Synapse (prefer not to disclose version unless absolutely needed)

### Will you send logs?

Yes

### Are you willing to provide a PR?

No