Determine if a shortcode has .Inner content

I am trying to let my shortcode either have inner content or not and I am not sure if this is a “lazy programming” situation or just impossible:

I would assume, that with a line like the following Hugo would ignore it, if there is no closing tag:

{{ with .Inner }}
<em>{{ . }}</em>
{{ end }}

Sample 1:

{{< shortcode >}}Something inside{{< /shortcode >}}

Expected: italic “Something inside”
Hugo: italic “Something inside”

Sample 2:

{{< shortcode >}}

Expected: nothing, there is no inner content
Hugo: italic EVERYTHING after the shortcode.

Is there a way to have one single shortcode serve both, calls with and without inner content? Or maybe, to start with, is there a way to determine if .Inner is existing or empty (which is two different states, one with a closing tag and one without)?

If Hugo is unable to have both versions in one shortcode layout I think that might be worth something exploring to be implemented?