add RoomMember.name which falls back to userId

this will prevent the crash when left members
have their displayname removed (another issue)

src/matrix/room/members/Heroes.js

@@ -22,12 +22,12 @@ function calculateRoomName(sortedMembers, summary) {
         if (sortedMembers.length > 1) {
             const lastMember = sortedMembers[sortedMembers.length - 1];
             const firstMembers = sortedMembers.slice(0, sortedMembers.length - 1);
-            return firstMembers.map(m => m.displayName).join(", ") + " and " + lastMember.displayName;
+            return firstMembers.map(m => m.name).join(", ") + " and " + lastMember.name;
         } else {
-            return sortedMembers[0].displayName;
+            return sortedMembers[0].name;
         }
     } else if (sortedMembers.length < countWithoutMe) {
-        return sortedMembers.map(m => m.displayName).join(", ") + ` and ${countWithoutMe} others`;
+        return sortedMembers.map(m => m.name).join(", ") + ` and ${countWithoutMe} others`;
     } else {
         // Empty Room
         return null;
@@ -81,7 +81,7 @@ export class Heroes {
         for (const member of updatedHeroMembers) {
             this._members.set(member.userId, member);
         }
-        const sortedMembers = Array.from(this._members.values()).sort((a, b) => a.displayName.localeCompare(b.displayName));
+        const sortedMembers = Array.from(this._members.values()).sort((a, b) => a.name.localeCompare(b.name));
         this._roomName = calculateRoomName(sortedMembers, summary);
     }
 

src/matrix/room/members/RoomMember.js

@@ -54,10 +54,23 @@ export class RoomMember {
         });
     }
 
+    /**
+     * @return {String?} the display name, if any
+     */
     get displayName() {
         return this._data.displayName;
     }
 
+    /**
+     * @return {String} the display name or userId
+     */
+    get name() {
+        return this._data.displayName || this._data.userId;
+    }
+
+    /**
+     * @return {String?} the avatar mxc url, if any
+     */
     get avatarUrl() {
         return this._data.avatarUrl;
     }