JS false positive on usage of let

The following JavaScript in one handler gives false errors on reuse of a variable. Misunderstanding the difference between let and var..

Component.onCompleted: {
var list = ['a', 'b']

for (let i in list)

{ console.log(i) }

for (let i = 0; i < list.length; i = i + 1) { console.log(i) }

}

For full reproducable app, see attached screenshot.