Unable to download the latest Heroic update using the built-in updater

When starting the launcher, it shows me a GUI, where I can choose to download the latest Heroic update, in the background. After a few minutes, however, it shows a GUI, telling me, that an error has ocurred, and that I should check the Heroic log.

Heroic log: https://paste.debian.net/hidden/6fa08fcf/