Restore the client 'loading' state

https://github.com/vector-im/element-call/pull/1173 regressed the client loading sequence, such that the app would pretend that you were signed out when it was really just loading your saved session. This makes the proper loading state appear again.

src/ClientContext.tsx

@@ -149,8 +149,9 @@ interface Props {
 export const ClientProvider: FC<Props> = ({ children }) => {
   const history = useHistory();
 
+  // null = signed out, undefined = loading
   const [initClientState, setInitClientState] = useState<
-    InitResult | undefined
+    InitResult | null | undefined
   >(undefined);
 
   const initializing = useRef(false);
@@ -162,14 +163,7 @@ export const ClientProvider: FC<Props> = ({ children }) => {
     initializing.current = true;
 
     loadClient()
-      .then((maybeClient) => {
-        if (!maybeClient) {
-          logger.error("Failed to initialize client");
-          return;
-        }
-
-        setInitClientState(maybeClient);
-      })
+      .then(setInitClientState)
       .catch((err) => logger.error(err))
       .finally(() => (initializing.current = false));
   }, []);
@@ -264,20 +258,22 @@ export const ClientProvider: FC<Props> = ({ children }) => {
     }, [initClientState?.client, setAlreadyOpenedErr, t])
   );
 
-  const state: ClientState = useMemo(() => {
+  const state: ClientState | undefined = useMemo(() => {
     if (alreadyOpenedErr) {
       return { state: "error", error: alreadyOpenedErr };
     }
 
-    let authenticated = undefined;
-    if (initClientState) {
-      authenticated = {
-        client: initClientState.client,
-        isPasswordlessUser: initClientState.passwordlessUser,
-        changePassword,
-        logout,
-      };
-    }
+    if (initClientState === undefined) return undefined;
+
+    const authenticated =
+      initClientState === null
+        ? undefined
+        : {
+            client: initClientState.client,
+            isPasswordlessUser: initClientState.passwordlessUser,
+            changePassword,
+            logout,
+          };
 
     return { state: "valid", authenticated, setClient };
   }, [alreadyOpenedErr, changePassword, initClientState, logout, setClient]);
@@ -308,7 +304,7 @@ type InitResult = {
   passwordlessUser: boolean;
 };
 
-async function loadClient(): Promise<InitResult> {
+async function loadClient(): Promise<InitResult | null> {
   if (widget) {
     // We're inside a widget, so let's engage *matryoshka mode*
     logger.log("Using a matryoshka client");
@@ -322,7 +318,8 @@ async function loadClient(): Promise<InitResult> {
     try {
       const session = loadSession();
       if (!session) {
-        throw new Error("No session stored");
+        logger.log("No session stored; continuing without a client");
+        return null;
       }
 
       logger.log("Using a standalone client");