diff --git a/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js b/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js
--- a/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js
+++ b/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js
@@ -55,10 +55,19 @@
         dmOperation;
       const { threadInfos } = utilities;
 
-      const messageDataWithMessageInfos =
-        createAddViewerToThreadMembersMessageDataWithInfoFromDMOp(dmOperation);
-      const { rawMessageInfo } = messageDataWithMessageInfos;
-      const rawMessageInfos = messageID ? [rawMessageInfo] : [];
+      let rawMessageInfos: Array<RawMessageInfo> = [];
+      let messageDataWithMessageInfos: ?{
+        +messageData: AddMembersMessageData,
+        +rawMessageInfo: RawMessageInfo,
+      } = null;
+      if (messageID) {
+        messageDataWithMessageInfos =
+          createAddViewerToThreadMembersMessageDataWithInfoFromDMOp(
+            dmOperation,
+          );
+        const { rawMessageInfo } = messageDataWithMessageInfos;
+        rawMessageInfos = [rawMessageInfo];
+      }
 
       const threadID = existingThreadDetails.threadID;
       const currentThreadInfo = threadInfos[threadID];
@@ -131,7 +140,9 @@
         ];
 
         const notificationsCreationData = {
-          messageDatasWithMessageInfos: [messageDataWithMessageInfos],
+          messageDatasWithMessageInfos: messageDataWithMessageInfos
+            ? [messageDataWithMessageInfos]
+            : [],
           thickRawThreadInfos: {
             [threadID]: resultThreadInfo,
           },
@@ -177,7 +188,9 @@
         },
       ];
       const notificationsCreationData = {
-        messageDatasWithMessageInfos: [messageDataWithMessageInfos],
+        messageDatasWithMessageInfos: messageDataWithMessageInfos
+          ? [messageDataWithMessageInfos]
+          : [],
         thickRawThreadInfos: {
           [threadID]: resultThreadInfo,
         },