now i passed 1 but failed 1 still.
error:

Expected: 0, instead got: undefined

. i was returning 0
if (array == null || array === 1 ) {
return 0;
}

not sure about the issue

Change return a>b to return b-a and you should be good :). You should always sort an array based on their value and not a comparsion of their values. Otherwise it will act on their Boolean value (true or false), since it's a comparsion operator, and will not sort based on their actual value. See more here.