libelektra: Sign in/Register fails

I tried to convert a snippet on the website, but got the error: undefined

The problem is not (only) about that the conversion does not work (might be a problem with a plugin), but that no useful error message is shown:

Snippet conversion
APP.CONVERSION.NOTIFICATION.MESSAGE..

Used plugins

Input:
- Plugin: line
- Format: line
- Additional config: 
Output:
- Plugin: simpleini
- Format: ini
- Additional config: % %

Input configuration

a = b

Last output configuration

Additional information