Appian Developer course 【Exercixe8: Process Modeling 101,Part 1】got error

Try passing the value in the key-value pair (make it a habit) i.e.
vehicleId: 1

And next thing is to cast the array into a single value. Use the below code to cast your output. 

cast(
  typeof(type!yourCDTName),
  
)

Try making use of For Each func and pass value .

it will help in getting all data .Example

a!foreach(items: index(yourqueried data,"data",1,null), expression:cast( typeof(type!your cdt name just type rest appian will help),fv!item)

if want for all just remove 1 .