Can we have a config param similar to showSummary but which ONLY shows a value set in a page's frontmatter

[venteto]

Something similar to this:

[list]
  showDescription = true
  showSummary = false

showSummary does not discriminate between whether I have intentionally set a value in front matter, and if I do not, then it falls back to display arbitrary content following the frontmatter, which is not what I want.

I can work around this by doing thus in the frontmatter:

summary: " "

But then I suspect in the list page some extra space is added to list entries, when I would prefer to not have any blank space following list entries that do not have a genuine summary explicitly set in the frontmatter (I don't mean a frontmatter summary hack, but an intentional summary of the actual content of the page).