Merge branch 'handle-ap-fetcher-when-not-json' into 'master'

Handle ActivityPub Fetcher returning text that's not JSON

See merge request framasoft/mobilizon!861

lib/federation/activity_pub/fetcher.ex

@@ -59,6 +59,10 @@ defmodule Mobilizon.Federation.ActivityPub.Fetcher do
         Logger.warn("Object origin check failed")
         {:error, "Object origin check failed"}
 
+      # Returned content is not JSON
+      {:ok, data} when is_binary(data) ->
+        {:error, "Failed to parse content as JSON"}
+
       {:error, err} ->
         {:error, err}
     end