Surprisingly, the code snippet below is generating an error, even though the variable a has been narrowed down to type string in the line const b = a.
It's worth noting that when I assign a to b, b does not encounter the same issue.
function test(a: string | undefined) {
if (a) {
const b = a
const x = false && a.length // Error: 'a' is possibly 'undefined'
const y = false && b.length // No error
}
}
What could be causing this unexpected behavior? This code example might not be particularly functional since both x and y are simply false. However, I sometimes use false&& as a way to easily comment out code (especially in JSX where traditional commenting can be more complex), but then these errors pop up.