make sure the left member convo exist in rendering GroupUpdate

ts/models/message.ts

@@ -128,6 +128,7 @@ export class MessageModel extends Backbone.Model<MessageAttributes> {
   public getDescription() {
     if (this.isGroupUpdate()) {
       const groupUpdate = this.get('group_update');
+
       const ourPrimary = window.textsecure.storage.get('primaryDevicePubKey');
       if (
         groupUpdate.left === 'You' ||
@@ -136,7 +137,10 @@ export class MessageModel extends Backbone.Model<MessageAttributes> {
           groupUpdate.left[0] === ourPrimary)
       ) {
         return window.i18n('youLeftTheGroup');
-      } else if (groupUpdate.left) {
+      } else if (
+        (groupUpdate.left && Array.isArray(groupUpdate.left) && groupUpdate.left.length === 1) ||
+        typeof groupUpdate.left === 'string'
+      ) {
         return window.i18n(
           'leftTheGroup',
           ConversationController.getInstance().getContactProfileNameOrShortenedPubKey(
@@ -144,7 +148,6 @@ export class MessageModel extends Backbone.Model<MessageAttributes> {
           )
         );
       }
-
       if (groupUpdate.kicked === 'You') {
         return window.i18n('youGotKickedFromGroup');
       }
@@ -373,7 +376,10 @@ export class MessageModel extends Backbone.Model<MessageAttributes> {
           type: 'remove',
           isMe: true,
         });
-      } else {
+      } else if (
+        typeof groupUpdate.left === 'string' ||
+        (Array.isArray(groupUpdate.left) && groupUpdate.left.length === 1)
+      ) {
         changes.push({
           type: 'remove',
           contacts: _.map(

ts/receiver/closedGroups.ts

@@ -449,6 +449,12 @@ async function performIfValid(
     await removeFromCache(envelope);
     return;
   }
+  // make sure the conversation with this user exist (even if it's just hidden)
+  await ConversationController.getInstance().getOrCreateAndWait(
+    sender,
+    ConversationTypeEnum.PRIVATE
+  );
+
   if (groupUpdate.type === Type.NAME_CHANGE) {
     await handleClosedGroupNameChanged(envelope, groupUpdate, convo);
   } else if (groupUpdate.type === Type.MEMBERS_ADDED) {
@@ -531,6 +537,12 @@ async function handleClosedGroupMembersAdded(
   }
 
   const members = [...oldMembers, ...membersNotAlreadyPresent];
+  // make sure the conversation with those members (even if it's just hidden)
+  await Promise.all(
+    members.map(async m =>
+      ConversationController.getInstance().getOrCreateAndWait(m, ConversationTypeEnum.PRIVATE)
+    )
+  );
 
   const groupDiff: ClosedGroup.GroupDiff = {
     joiningMembers: membersNotAlreadyPresent,
@@ -748,6 +760,7 @@ async function handleClosedGroupMemberLeft(envelope: EnvelopePlus, convo: Conver
   const groupDiff: ClosedGroup.GroupDiff = {
     leavingMembers: [sender],
   };
+
   await ClosedGroup.addUpdateMessage(convo, groupDiff, 'incoming', _.toNumber(envelope.timestamp));
   convo.updateLastMessage();
   // if a user just left and we are the admin, we remove him right away for everyone by sending a MEMBERS_REMOVED message so no need to add him as a zombie