`prepare_release` doesn't add the "version" field to CodeMeta if it is not present

The script prepare_release updates the fields version and dateModified in the CodeMeta file:

...
    if 'version' in codemeta.data:
        codemeta.data['version'] = settings.VERSION

    if 'dateModified' in codemeta.data:
        codemeta.data['dateModified'] = settings.DATE or date.today().strftime('%Y-%m-%d')
...

Yet, these fields are not created if they don't exist. Is this an expected behavior? Wouldn't it be better that the fields are added to the file?

@axel.loewe @jochen