Optional Lab error

Hi, while solving optional lab, I reach the nex error:

“errmsg” : "Bad projection specification, cannot exclude fields other than ‘_id’

What I tried is to find if $setIntersection $isArray (have common values), returning 1, if not, 0:

var pipeline = [ 
{
	$project:
	{
		"cast": 1,
		"directors": 1,
		"writers": 1,
		laborOfLove: {if: {$isArray: {$setIntersection: ["$cast", "$directors", "$writers"]}}, then: 1, else: 0 }
	}
},
{ 
	$match: 
	{
		laborOfLove: 1
	}
}
]

But i have this error I can’t figured out how tos solve it.

Thanks

When it return 0, it means you try to exclude the field laborOfLove, hence the error message