Can't download or install Keka from the Mac App Store

# Workaround

As suggested by @VinBoiSoft and successfully tested by @ulrich2021, **killing the process `appstoreagent` seems to temporarily fix the issue**.

### 👉 Follow these steps:

1. Open the Mac App Store and go to the Keka page
2. In the Terminal execute this command: `killall appstoreagent`
3. Immediately click on download Keka in the Mac App Store page

You can also stop the `appstoreagent` process using the `Activity Monitor.app`.

## Original issue

### Configuration
- Keka version: latest before update
- macOS version: Mojave 10.14.6 latest

Hi! I'm no technician, can't be too precise ...
My problem: I can't reinstall Keka from the apple app store. At first it refuses to load the last update a few days ago. Then I deleted Keka on my drive tried a reinstallation. Now this failed, too.
Any ideas to help me out?