Following the instructions on the readme produces an error

I've just tried to follow the instructions on the readme, but I get this error:

(base) rodri@rodri-B450-AORUS-PRO:~$ cookiecutter https://git.km3net.de/templates/python-project.git
author [Leo Szilard]: rgracia
Unable to render variable 'email'
Error message: list object has no element 1
Context: {
    "cookiecutter": {
        "_extensions": [
            "jinja2_time.TimeExtension"
        ],
        "_test": "{% print('hello') %}",
        "author": "Leo Szilard",
        "description": "The {{ cookiecutter.project_name }} project",
        "email": "{{cookiecutter.author.lower()[0] + cookiecutter.author.split()[1].lower()}}@km3net.de",
        "gitlab_repo_path": "https://git.km3net.de/{{ cookiecutter.gitlab_username + '/' + cookiecutter.project_slug }}",
        "gitlab_username": "{{cookiecutter.email.split('@')[0]}}",
        "project_name": "Awesome",
        "project_slug": "{{ cookiecutter.project_name.lower().replace(' ', '_') }}",
        "version": "0.1.0"
    }
}

Is there some aditional step to do that's not written in the description?