Remove thumbnail in slider when only one image are selected

Hi,

When the gallery is empty, but only one selected image are visible (the featured image of the post) it still appears in the slider. I would like to remove that thumbnail so only the full size image are visible.

If it’s more than one, that’s OK for me, but when it’s just one image.. I don’t want both the full size and the thumbnail.

Is it possible?

Thanks!

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