let self::someVar = "";

[tecworks-dev]

namespace Demo;

class MyClass {

protected static someVar;

public static function setVar() {
    let self::someVar = "";
}

}

let self::someVar = "";
[ERROR] Internal extension compilation failed. Check compile-errors.log for more information.
but
let self::someVar = "123";
let self::someVar = null;
works fine