Support sync without filters for guest access

Author: hughns

src/matrix/Sync.js

@@ -176,11 +176,17 @@ export class Sync {
     async _syncRequest(syncToken, timeout, log) {
         let {syncFilterId} = this._session;
         if (typeof syncFilterId !== "string") {
-            this._currentRequest = this._hsApi.createFilter(this._session.user.id, {room: {state: {lazy_load_members: true}}}, {log});
-            syncFilterId = (await this._currentRequest.response()).filter_id;
+            try {
+                this._currentRequest = this._hsApi.createFilter(this._session.user.id, {room: {state: {lazy_load_members: true}}}, {log});
+                syncFilterId = (await this._currentRequest.response()).filter_id;
+            } catch (err) {
+                // if the server doesn't support filters, we'll just have to do without
+                log.log('Sync filters aren\'t available, falling back to no filter');
+                syncFilterId = "filteringNotAvailable";
+            }
         }
         const totalRequestTimeout = timeout + (80 * 1000);  // same as riot-web, don't get stuck on wedged long requests
-        this._currentRequest = this._hsApi.sync(syncToken, syncFilterId, timeout, {timeout: totalRequestTimeout, log});
+        this._currentRequest = this._hsApi.sync(syncToken, syncFilterId === "filteringNotAvailable" ? undefined : syncFilterId, timeout, {timeout: totalRequestTimeout, log});
         const response = await this._currentRequest.response();
 
         const isInitialSync = !syncToken;