Various refactoring and typespec improvements

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

lib/service/workers/background.ex

@@ -11,11 +11,23 @@ defmodule Mobilizon.Service.Workers.Background do
   use Mobilizon.Service.Workers.Helper, queue: "background"
 
   @impl Oban.Worker
+  @spec perform(Job.t()) ::
+          {:ok, Actor.t()}
+          | {:error,
+             :actor_not_found | :bad_option_value_for_reserve_username | Ecto.Changeset.t()}
   def perform(%Job{args: %{"op" => "delete_actor", "actor_id" => actor_id} = args}) do
-    with reserve_username when is_boolean(reserve_username) <-
-           Map.get(args, "reserve_username", true),
-         %Actor{} = actor <- Actors.get_actor(actor_id) do
-      ActorSuspension.suspend_actor(actor, reserve_username: reserve_username)
+    case Map.get(args, "reserve_username", true) do
+      reserve_username when is_boolean(reserve_username) ->
+        case Actors.get_actor(actor_id) do
+          %Actor{} = actor ->
+            ActorSuspension.suspend_actor(actor, reserve_username: reserve_username)
+
+          nil ->
+            {:error, :actor_not_found}
+        end
+
+      _ ->
+        {:error, :bad_option_value_for_reserve_username}
     end
   end