Lack of type narrowing from defined()

[multimeric]

Say I have the following task:

version 1.0

task Test {
  input {
    Int? optional
  }

  command {}

  output {
    Int x = if defined(optional) then optional else 0
  }
}

Validation with miniwdl will fail:

$ miniwdl check miniwdl_narrowing.wdl
(miniwdl_narrowing.wdl Ln 11 Col 13) Expected Int instead of Int? -- to coerce T? X into T, try select_first([X,defaultValue]) or select_first([X]) (which might fail at runtime); to coerce Array[T?] X into Array[T], try select_all(X)
        Int x = if defined(optional) then optional else 0
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* Hint: for compatibility with older existing WDL code, try setting --no-quant-check to relax quantifier validation rules.

Using miniWDL 1.12.1