Why can a use block not safely initialize a var?

Why does this give a compile error?

val autoClosable = MyAutoClosable()
var myVar: MyType
autoClosable.use {
    myVar= it.foo()
}
println(myVar) // Error: Variable 'myVar' must be initialized

Maybe the compiler just sees { myVar= it.foo() } as a function that is passed to another function and has no knowledge about when or even if it will be executed?

But since use is not just a function but Kotlin's replacement for Java's try-with-resource, some special knowledge about it would be appropriate, wouldn't it? Right now, I am forced to initialize myVar with some dummy value, which is not in the spirit of Kotlin at all.