Account for nil schema_node in ArgumentsOfCorrectType suggestions

lib/absinthe/phase/document/validation/arguments_of_correct_type.ex

@@ -84,6 +84,7 @@ defmodule Absinthe.Phase.Document.Validation.ArgumentsOfCorrectType do
           case Type.unwrap(node.schema_node) do
             %Type.Scalar{} -> []
             %Type.Enum{} -> []
+            nil -> []
             _ -> suggested_field_names(node.schema_node, child.name)
           end
 

test/absinthe/phase/document/validation/arguments_of_correct_type_test.exs

@@ -974,6 +974,36 @@ defmodule Absinthe.Phase.Document.Validation.ArgumentsOfCorrectTypeTest do
     end
   end
 
+  describe "Invalid Custom Scalar value" do
+    test "Invalid scalar input on mutation, no suggestion" do
+      assert_fails_validation(
+        """
+        mutation($scalarInput: CustomScalar) {
+          createDog(customScalarInput: $scalarInput)
+        }
+        """,
+        [
+          variables: %{
+            "scalarInput" => [
+              %{
+                "foo" => "BAR"
+              }
+            ]
+          }
+        ],
+        [
+          bad_argument(
+            "customScalarInput",
+            "CustomScalar",
+            ~s($scalarInput),
+            2,
+            [@phase.unknown_field_error_message("foo")]
+          )
+        ]
+      )
+    end
+  end
+
   describe "Directive arguments" do
     test "with directives of valid types" do
       assert_passes_validation(

test/support/fixtures/pets_schema.ex

@@ -123,6 +123,11 @@ defmodule Absinthe.Fixtures.PetsSchema do
     field :string_list_field, list_of(:string)
   end
 
+  scalar :custom_scalar do
+    parse & &1
+    serialize & &1
+  end
+
   object :complicated_args do
     field :int_arg_field, :string do
       arg :int_arg, :integer
@@ -194,6 +199,12 @@ defmodule Absinthe.Fixtures.PetsSchema do
     field :complicated_args, :complicated_args
   end
 
+  mutation do
+    field :create_dog, :dog do
+      arg :custom_scalar_input, non_null(:custom_scalar)
+    end
+  end
+
   directive :on_query do
     on [:query]
   end