add_ribbons can't handle NA values

The plotly function add_ribbons() doesn't function properly when cases in the middle or at the end have NA values. These lead to a weird behaviour where parts of the ribbons are missing or drawn in wrong places (see Plots 1 & 3). When the connectgaps-Attribute is set to TRUE for the ribbon the bug doesn't appear (see Plot 2).
NA values in the beginning don't seem to be a problem as well (see Plot 3, Red Trace 2).

The same behaviour has also been reported with ggplot and plotly in issue #1060. But because it may either be two separate problems or just a problem in plotly itself also affecting the ggplot visualization I decided to open this separate issue.

Commencez avec la fonction R add_ribbons() et reproduisez le comportement en utilisant les Plots 1–3 liés, en vous concentrant sur les valeurs NA au milieu et à la fin. Comparez le résultat avec connectgaps défini sur TRUE et avec l’issue #1060 associée de ggplot et plotly ; le travail est considéré comme terminé lorsque les ribbons sont rendus aux bons endroits sans nécessiter connectgaps.