Fix posts and rework graphql errors

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/graphql/middleware/error_handler.ex

@@ -0,0 +1,21 @@
+defmodule Mobilizon.GraphQL.Middleware.ErrorHandler do
+  @moduledoc """
+  Absinthe Error Handler
+  """
+  alias Mobilizon.GraphQL.Error
+
+  @behaviour Absinthe.Middleware
+  @impl true
+  def call(resolution, _config) do
+    errors =
+      resolution.errors
+      |> Enum.map(&Error.normalize/1)
+      |> List.flatten()
+      |> Enum.map(&to_absinthe_format/1)
+
+    %{resolution | errors: errors}
+  end
+
+  defp to_absinthe_format(%Error{} = error), do: Map.from_struct(error)
+  defp to_absinthe_format(error), do: error
+end