Don't crash on activity handling problems.

lib/pleroma/web/ostatus/ostatus.ex

@@ -32,6 +32,7 @@ def handle_incoming(xml_string) do
       {:xmlObj, :string, verb} = :xmerl_xpath.string('string(/entry/activity:verb[1])', entry)
       Logger.debug("Handling #{verb}")
 
+      try do
         case verb do
           'http://activitystrea.ms/schema/1.0/follow' ->
             with {:ok, activity} <- FollowHandler.handle(entry, doc), do: activity
@@ -50,7 +51,15 @@ def handle_incoming(xml_string) do
                 nil
             end
         end
+      rescue
+        e ->
+          Logger.error("Error occured while handling activity")
+          Logger.error(inspect(e))
+          nil
+      end
     end)
+    |> Enum.filter(&(&1))
+
     {:ok, activities}
   end