Fix Single Sign-on

https://github.com/matrix-org/matrix-react-sdk/pull/2826 checked
that we had data in the crypto store if the had credentials in
localStorage. However, SSO stores creds in localStorage and then
redirects the browser to remove the loginToken parameter from the
URL without starting crypto, so after the redirect, we see creds
in localStorage but no crypto data, and error.

Fix by marking when we've successfully initialised crypto and only
erroring if that flag is set.

Fixes https://github.com/vector-im/riot-web/issues/9695

src/MatrixClientPeg.js

@@ -121,6 +121,7 @@ class MatrixClientPeg {
             // check that we have a version of the js-sdk which includes initCrypto
             if (this.matrixClient.initCrypto) {
                 await this.matrixClient.initCrypto();
+                StorageManager.setCryptoInitialised(true);
             }
         } catch (e) {
             if (e && e.name === 'InvalidCryptoStoreError') {