Absinthe.run/3 operation_name not allowing null in non current operations

If submitting a bug, please provide the following:

Environment

Elixir version (elixir -v): 1.8.0
Absinthe version (mix deps | grep absinthe): 1.4.13

Expected behavior

Based on the documentation for Absinthe.run/3, I would expect to be able to pass the following document:

mutation Create($createResource: CreateResourceInput!) {
    create(resource: $createResource) { name, id }
}

mutation Update($updateResource: UpdateResourceInput!) {
    create(resource: $updateResource) { name, id }
}

and run Absinthe.run(document, MyApp.Schema, variables: %{...}, operation_name: "Create"), which would in turn only execute the first mutation in the document.

Actual behavior

Instead, all mutations run regardless of which operation_name I provide, and I get errors for missing fields, etc., for mutations that I did not intend to run. I have done the following to troubleshoot:

Try using queries instead of mutations. This works, which leads me to believe Absinthe.run/3 does not currently support operation_name: for documents with mutations.
Pass an invalid operation_name. As expected, this throws an error saying Must provide a valid operation name if query contains multiple operations.
Ensure the mutation succeeds when I move each mutation into its own document, and run individually.

Below is the error I get when I attempt to run a test against a single mutation in the document:

code:  assert {:ok, %{data: data}} = result
right: {:ok,
%{
  errors: [
    %{
      locations: [%{column: 0, line: 42}],
      message: "In argument \"modifier_choice\": Expected type \"DeleteModifierChoiceInput!\", found null."
    },
    %{
      locations: [%{column: 0, line: 41}],
      message: "Variable \"modifier_choice\": Expected non-null, found null."
    },
    %{
      locations: [%{column: 0, line: 37}],
      message: "In argument \"modifier_choice\": Expected type \"UpdateModifierChoiceInput!\", found null."
    },
    %{
      locations: [%{column: 0, line: 36}],
      message: "Variable \"modifier_choice\": Expected non-null, found null."
    },
    %{
      locations: [%{column: 0, line: 32}],
      message: "In argument \"modifier_choice\": Expected type \"CreateModifierChoiceInput!\", found null."
    },
    %{
      locations: [%{column: 0, line: 31}],
      message: "Variable \"modifier_choice\": Expected non-null, found null."
    },
    %{
      locations: [%{column: 0, line: 27}],
      message: "In argument \"modifier_group\": Expected type \"DeleteModifierGroupInput!\", found null."
    },
    %{
      locations: [%{column: 0, line: 26}],
      message: "Variable \"modifier_group\": Expected non-null, found null."
    },
    %{
      locations: [%{column: 0, line: 22}],
      message: "In argument \"modifier_group\": Expected type \"UpdateModifierGroupInput!\", found null."
    },
    %{
      locations: [%{column: 0, line: 21}],
      message: "Variable \"modifier_group\": Expected non-null, found null."
    },
    %{
      locations: [%{column: 0, line: 17}],
      message: "In argument \"modifier_group\": Expected type \"CreateModifierGroupInput!\", found null."
    },
    %{
      locations: [%{column: 0, line: 16}],
      message: "Variable \"modifier_group\": Expected non-null, found null."
    },
    %{
      locations: [%{column: 0, line: 12}],
      message: "Argument \"product\" has invalid value $product.\nIn field \"description\": Unknown field."
    },
    %{
      locations: [%{column: 0, line: 2}],
      message: "Argument \"product\" has invalid value $product.\nIn field \"name\": Expected type \"String!\", found null.\nIn field \"category\": Expected type \"String!\", found null.\nIn field \"catalogId\": Expected type \"ID!\", found null.\nIn field \"basePrice\": Expected type \"CurrencyInput!\", found null.\nIn field \"id\": Unknown field."
    }
  ]
}}

It appears all the mutations that I did not intend to run are throwing errors, as I have not provide valid variables to them.

absinthe-graphql / absinthe