[rocqua]

Part of the reason OP liked the `if assignment` was to avoid polluting the higher-level scope with a variable that is only needed during the if statement.

Your solution fixes the error, but at the cost of losing the upside OP saw.

[jaggederest]

Is there no equivalent to a lexical scope let definition?

let {

  var err := error
  
  scoped code

}

[usrbinbash]

Of course there is:

    {
        var err error
        scoped code
    }

[ptomato]

yes, you can wrap code in {} to scope it.