Incorrect behaviour of `ArgBuilder` containing only nullable fields when input is null

[kyri-petrou]

Given the following case class:

case class Foo(value1: Option[String], value2: Option[String]) derives ArgBuilder

I expect that the derived ArgBuilder#build should work in the following ways:

1. Input: {}, output: Right(Foo(None, None))
2. Input: null, output Left(ExecutionError("bla"))

However, currently both cases succeed with Foo(None, None). Can be reproduced with the following test that should pass but fails since the first condition is not Left

    suite("derived build")(
      test("should fail when null is provided for case class with optional fields") {
        case class Foo(value: Option[String])
        val ab = ArgBuilder.gen[Foo]
        assertTrue(
          ab.build(NullValue).isLeft,
          ab.build(ObjectValue(Map())).isRight
        )
      }
    )

PS: This is not a problem when validation is enabled as an error will be raised during the validation phase

[kyri-petrou]

@ghostdogpr are you aware of anything that relies on the ArgBuilder succeeding when null is provided instead of {}?

[ghostdogpr]

Hmm yeah that looks like a bug.