Export Chat with choose amount of messages pointing to a low amount results to an empty array

### Steps to reproduce

1. You are in a chat room with quite some messages sent in it
2. In the chat its information panel press Chat export
3. You select "Choose the amount of messages" in the dropdown
4. You add 5 as input for the amount of messages and press export
5. Open up the downloaded export

### Outcome

#### What did you expect?
- The export contains the expected amount of messages

#### What happened instead?
- The export contains 0 messages (doesn't matter which format you selected, the outcome is the same)

### Operating system

_No response_

### Browser information

_No response_

### URL for webapp

_No response_

### Application version

_No response_

### Homeserver

_No response_

### Will you send logs?

No

Start by reproducing the Chat export flow from a room's information panel, selecting a custom amount of 5 messages and checking the downloaded export. Trace how the amount input is passed into the export operation; done means the export contains the requested messages in each supported format.

Written by the indexing model from the issue text.