FIX: don't blow up on badly encoding incoming email body

app/serializers/incoming_email_details_serializer.rb

@@ -33,14 +33,19 @@ class IncomingEmailDetailsSerializer < ApplicationSerializer
   end
 
   def subject
-    @mail.subject.presence || "(no subject)"
+    @mail.subject.presence || I18n.t("emails.incoming.no_subject")
   end
 
   def body
     body   = @mail.text_part.decoded rescue nil
     body ||= @mail.html_part.decoded rescue nil
     body ||= @mail.body.decoded      rescue nil
-    body.strip.truncate_words(100, escape: false)
+
+    return I18n.t("emails.incoming.no_body") if body.blank?
+
+    body.encode("utf-8", invalid: :replace, undef: :replace, replace: "")
+      .strip
+      .truncate_words(100, escape: false)
   end
 
 end

config/locales/server.en.yml

@@ -63,6 +63,8 @@ en:
       default_subject: "This topic needs a title"
       show_trimmed_content: "Show trimmed content"
       maximum_staged_user_per_email_reached: "Reached maximum number of staged users created per email."
+      no_subject: "(no subject)"
+      no_body: "(no body)"
       errors:
         empty_email_error: "Happens when the raw mail we received was blank."
         no_message_id_error: "Happens when the mail has no 'Message-Id' header."