Create sub module with atom name

[shahryarjb]

@zachallaun

defmacro sub_field(name, type, opts \\ [], do: block) do
    ast = register_struct(block, opts)

    name =
      name
      |> Atom.to_string()
      |> Macro.camelize()
      |> String.to_atom()

    quote unquote: false, bind_quoted: [name: name, ast: ast] do
      module_name = Module.concat(__MODULE__, name)

      defmodule unquote(module_name) do
        unquote(ast)
      end
    end
  end

I have this eror for this:

error: unquote called outside quote
  test/guarded_struct_test.exs:521: MishkaDeveloperToolsTest.GuardedStructTest.TestNestedStruct (module)