I intentionally corrected it, because vanilla JS arrays used to behave like this in some contexts, but I'm not even sure about which ones still.

Since the "Array" is a reference to the prototype, I think it might be outdated due to changes in undefined behavior of runtimes when serializing array objects, or logging them.

I'm pretty sure that [object Array] used to be the result of logging an array at some point.

  Object.prototype.toString

always returns the result of

  Array.prototype.join

per spec, afaik, so for an empty array it's the empty string.