fix: function :function_clause.__struct__/0 is undefined

[fuelen]

This error happens when exception is raised from absinthe

[error] Task #PID<0.3034.0> started from SpandexDatadog.ApiServer terminating
** (UndefinedFunctionError) function :function_clause.__struct__/0 is undefined (module :function_clause is not available)
    :function_clause.__struct__()
    (spandex_datadog 1.0.0) lib/spandex_datadog/api_server.ex:271: SpandexDatadog.ApiServer.add_error_type/2
    (spandex_datadog 1.0.0) lib/spandex_datadog/api_server.ex:264: SpandexDatadog.ApiServer.add_error_data/2
    (spandex_datadog 1.0.0) lib/spandex_datadog/api_server.ex:244: SpandexDatadog.ApiServer.meta/1
    (spandex_datadog 1.0.0) lib/spandex_datadog/api_server.ex:230: SpandexDatadog.ApiServer.format/3
    (elixir 1.11.2) lib/enum.ex:1399: Enum."-map/2-lists^map/1-0-"/2
    (elixir 1.11.2) lib/enum.ex:1399: Enum."-map/2-lists^map/1-0-"/2
    (spandex_datadog 1.0.0) lib/spandex_datadog/api_server.ex:196: SpandexDatadog.ApiServer.send_and_log/2
    (spandex_datadog 1.0.0) lib/spandex_datadog/api_server.ex:172: anonymous fn/3 in SpandexDatadog.ApiServer.handle_call/3
    (elixir 1.11.2) lib/task/supervised.ex:90: Task.Supervised.invoke_mfa/2
    (stdlib 3.12.1) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
Function: #Function<14.89247124/0 in SpandexDatadog.ApiServer.handle_call/3>
    Args: []

[sourcelevel-bot]

Hello, @fuelen! This is your first Pull Request that will be reviewed by SourceLevel, an automatic Code Review service. It will leave comments on this diff with potential issues and style violations found in the code as you push new commits. You can also see all the issues found on this Pull Request on its review page. Please check our documentation for more information.

[GregMefford]

Thanks for pointing this out! I have a small tweak that I want to make to this, but I'll just add a commit to this branch and then merge it. ❤️ 🚀

[GregMefford]

Hm, it looks like I can't push to this branch on your fork for some reason. No problem! I'll just merge this and separately push the new commits in another PR. Thanks again! 🚀