Hello,
I am trying to extract unique dates from a filter array of dates using compose action with union function but encountered the following error:

I checked the expression but unable to spot any problem with it. Much appreciate any help to troubleshoot this issue. The union expression I used is
union(outputs('Compose_2__-__Get_Booking_Dates_'),outputs('Compose_2__-__Get_Booking_Dates_'))

Thanks in advance for your help.
@ekarim2020
@reza dorrani