Playground - Core library error

I’m trying to run some simple code in the Playground and am getting an error when using auto-run feature:

let mult = (a, b) => a * b

let n = [1,2,3,4]->Array.reduce(1, mult)

Console.log(n)

Output error:
{"stack":"ReferenceError: Core__Array is not defined\n at eval (eval at <anonymous> (about:srcdoc:6:15), <anonymous>:6:9)\n at eval (<anonymous>)\n at about:srcdoc:39:15","message":"Core__Array is not defined"}