Check if email participants are null

javascript/src/utilities/emailUtilities.js

@@ -17,6 +17,10 @@ const SIGNATURE_CONTENT_TYPE = "application/pkcs7-signature";
 export const DEFAULT_ATTACHMENT_NAME = 'attachment';
 
 const splitParticipants = participantsList => {
+  if (!participantsList) {
+    return [];
+  }
+
   const participants = participantsList.map(participants => participants.split(",").map(p => p.trim()));
   return union.apply(null, participants);
 };