Improve changing current actor

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

lib/graphql/resolvers/user.ex

@@ -311,19 +311,20 @@ defmodule Mobilizon.GraphQL.Resolvers.User do
   def change_default_actor(
         _parent,
         %{preferred_username: username},
-        %{context: %{current_user: %User{id: user_id} = user}}
+        %{context: %{current_user: %User{} = user}}
       ) do
-    with %Actor{id: actor_id} = actor <- Actors.get_local_actor_by_name(username),
-         {:user_actor, true} <-
-           {:user_actor, actor_id in Enum.map(Users.get_actors_for_user(user), & &1.id)},
-         %User{} = user <- Users.update_user_default_actor(user_id, actor) do
-      {:ok, user}
-    else
-      {:user_actor, _} ->
-        {:error, :actor_not_from_user}
+    case Actors.get_local_actor_by_name(username) do
+      %Actor{id: actor_id} = actor ->
+        if actor_id in Enum.map(Users.get_actors_for_user(user), & &1.id) do
+          %User{} = user = Users.update_user_default_actor(user, actor)
+          {:ok, user}
+        else
+          {:error, dgettext("errors", "This profile does not belong to you")}
+        end
 
-      _error ->
-        {:error, :unable_to_change_default_actor}
+      nil ->
+        {:error,
+         dgettext("errors", "Profile with username %{username} not found", %{username: username})}
     end
   end