evaluator.EvaluateOutputFiles fails when overriding output property

[amannm-apple]

evaluator EvaluateOutputFiles fails with the following error:

–– Pkl Error ––
Cannot find method `toMap` in class `Null`.

1 | output.files.toMap().mapValues((_, it) -> it.text)
    ^^^^^^^^^^^^^^^^^^^^
at  (repl:text)

Available methods in class `Null`:
getClass
ifNonNull
toString

when evaluating the following document:

output {
  value = (module.toDynamic()) {
    output = "foo"
  }
}

[bioball]

This happens because output.files, indeed, is null. However, perhaps we can return an empty map in this case.

[Carpe-Wang]

@bioball hey, Can I do this (we can return an empty map in this case.)?

func (e *evaluator) EvaluateOutputFiles(ctx context.Context, source *ModuleSource) (map[string]string, error) {
	var out map[string]string
	err := e.EvaluateExpression(ctx, source, "output.files.toMap().mapValues((_, it) -> it.text)", &out)
	return out, err
}

In above code I want use the

err := e.EvaluateExpression(ctx, source, `
		if output.files != null {
			output.files.toMap().mapValues((_, it) -> it.text)
		} else {
			{}
		}`, &out)

to replace err := e.EvaluateExpression(ctx, source, "output.files.toMap().mapValues((_, it) -> it.text)", &out) to achieve return an empty map in this case.