Lexical declaration cannot appear in a single-statement context

[oljbo]

c# code is:

var jscode = @"
function fun(item){
    if (createmode == true) {
        let a = 'a';
        var b = 'b';
        if(a && b != null ) {
            let Maker = 'c';
            let obj = {a:a,Closed:1,Closer:Maker,CloseDate:new Date()};
            let rejust= null;
        }
    }
}

var createmode = true;
fun(null); 
";
var s1 = Uglify.Js(jscode, new NUglify.JavaScript.CodeSettings() { }).Code;

ths result is:
function fun(){if(createmode==!0){let t="a";var n="b";if(t&&n!=null)let n={a:t,Closed:1,Closer:"c",CloseDate:new Date}}}var createmode=!0;fun(null)

when I run the result in brower, It's has error:
SyntaxError: Lexical declaration cannot appear in a single-statement context

[trullock]

The issue is its outputting

if(predicate)
    let x = something

which is invalid.

As a workaround you can try,

1. use var if possible, but beware scope hoisting
2. the above code doesnt really make sense anyway, youre declaring something but not using it. You can probably avoid this issue just by refactoring a bit