federator: don't nest {:error, _} tuples

It makes decisions based on error sources harder since all possible
nesting levels need to be checked for. As shown by the return values
handled in the receiver worker something else still nests those,
but this is a first start.

lib/pleroma/web/federator.ex

@@ -117,7 +117,11 @@ def perform(:incoming_ap_doc, params) do
       e ->
         # Just drop those for now
         Logger.debug(fn -> "Unhandled activity\n" <> Jason.encode!(params, pretty: true) end)
-        {:error, e}
+
+        case e do
+          {:error, _} -> e
+          _ -> {:error, e}
+        end
     end
   end
 end

lib/pleroma/workers/receiver_worker.ex

@@ -24,13 +24,13 @@ def perform(%Job{args: %{"op" => "incoming_ap_doc", "params" => params}}) do
         {:discard, :already_present}
 
       # invalid data or e.g. deleting an object we don't know about anyway
-      {:error, {:error, {:validate, issue}}} ->
+      {:error, {:validate, issue}} ->
         Logger.info("Received invalid AP document: #{inspect(issue)}")
         {:discard, :invalid}
 
       # rarer, but sometimes there’s an additional :error in front
-      {:error, {:error, {:error, {:validate, issue}}}} ->
-        Logger.info("Received invalid AP document: (3e) #{inspect(issue)}")
+      {:error, {:error, {:validate, issue}}} ->
+        Logger.info("Received invalid AP document: (2e) #{inspect(issue)}")
         {:discard, :invalid}
 
       {:error, _} = e ->