Adding a check to find if returned value is not an object

I have a variable that retrieves value as below:

val = $(curl command ...)

val returns an object which looks as {"parm1":"****","data":"adfsdfsdaf"}

I want to add a validation for two conditions:

• val is either an object or
• val.data is null

I want to print a message "data not parsed correctly"

• when val is an object such as {"parm1":"****","data":"adfsdfsdaf"}

I want to print a message "data is null"

• when val is an null.

I have written below logic for it but it is not looking correct:

if [[ ${val} == null ]]; then
  echo "data not parsed correctly"
  exit 1

The correct value of val is adfsdfsdaf when the script should not exit.

With [tag:jq]

if val=$(curl ... \
         | jq 'try 
                 if .data != null 
                   then . 
                   else ("is null" | halt_error) 
                 end 
               catch
                 ("not an object" | halt_error)
            ' 2>&1
        )
then
    do_something_with_valid "$val"
else
    echo "error: $val" >&2
    exit 1
fi