Rewrite to use async / await

src/Lifecycle.js

@@ -65,14 +65,14 @@ import sdk from './index';
  *     Resolves to `true` if we ended up starting a session, or `false` if we
  *     failed.
  */
-export function loadSession(opts) {
+export async function loadSession(opts) {
+    try {
         let enableGuest = opts.enableGuest || false;
         const guestHsUrl = opts.guestHsUrl;
         const guestIsUrl = opts.guestIsUrl;
         const fragmentQueryParams = opts.fragmentQueryParams || {};
         const defaultDeviceDisplayName = opts.defaultDeviceDisplayName;
 
-    return Promise.resolve().then(() => {
         if (!guestHsUrl) {
             console.warn("Cannot enable guest access: can't determine HS URL to use");
             enableGuest = false;
@@ -91,8 +91,7 @@ export function loadSession(opts) {
                 guest: true,
             }, true).then(() => true);
         }
-        return _restoreFromLocalStorage();
-    }).then((success) => {
+        const success = await _restoreFromLocalStorage();
         if (success) {
             return true;
         }
@@ -103,9 +102,9 @@ export function loadSession(opts) {
 
         // fall back to login screen
         return false;
-    }).catch((e) => {
+    } catch (e) {
         return _handleLoadSessionFailure(e);
-    });
+    }
 }
 
 /**
@@ -199,10 +198,9 @@ function _registerAsGuest(hsUrl, isUrl, defaultDeviceDisplayName) {
 //      The plan is to gradually move the localStorage access done here into
 //      SessionStore to avoid bugs where the view becomes out-of-sync with
 //      localStorage (e.g. teamToken, isGuest etc.)
-function _restoreFromLocalStorage() {
-    return Promise.resolve().then(() => {
+async function _restoreFromLocalStorage() {
     if (!localStorage) {
-            return Promise.resolve(false);
+        return false;
     }
     const hsUrl = localStorage.getItem("mx_hs_url");
     const isUrl = localStorage.getItem("mx_is_url") || 'https://matrix.org';
@@ -220,19 +218,19 @@ function _restoreFromLocalStorage() {
 
     if (accessToken && userId && hsUrl) {
         console.log(`Restoring session for ${userId}`);
-            return _doSetLoggedIn({
+        await _doSetLoggedIn({
             userId: userId,
             deviceId: deviceId,
             accessToken: accessToken,
             homeserverUrl: hsUrl,
             identityServerUrl: isUrl,
             guest: isGuest,
-            }, false).then(() => true);
+        }, false);
+        return true;
     } else {
         console.log("No previous session found.");
-            return Promise.resolve(false);
+        return false;
     }
-    });
 }
 
 function _handleLoadSessionFailure(e) {