Max date between two columns and dealing with null values

Hi Community 

I have just used the following M Code to try and output the max date of two columns

= List.Max({[Appointment Date]}&{[Appointment Date]})

I used the code provided in the link below.

Solved: How to get a MAX date between two columns in a pow... - Microsoft Power BI Community

However I need help in editing the code so that it deals with null values. As you can see in my example below. I would expect the 

#1 null to be 14/03/2023  a (circled below).  # 2 null seems to be working

thank you

Richard