I'm trying to send some values in table to an email, the problem starts when it sends the date, I want it in this format "dd-mm-yy"

var fecha = new Date(registro.getRange("c16").getValue());
var fechaF = Utilities.formatDate(fecha, "GMT","DD-MM-YYYY");

The above code is used to transform the date, but when a cell that is a date is empty it sends me a date totally random.

It is table with multiple dates, and if I write the first it sends exactly the same, but if there is nothing it sends me a random date, and I want to send nothing, because having these dates in the email could be confusing.

What can I do to set the format, but also to not send anything if it is empty

Here is an example what is send to the email