MatrixClient.login persists access token but not device ID

[richvdh]

The /login endpoint returns, among other things, an access token and a device ID.

The access token is self-evidently important: it must be used for all future requests. MatrixClient.login persists the access token so that future methods on MatrixClient use it.

However, the device ID is also important, particularly for E2EE operations, since the device ID is used in signing operations. However, MatrixClient.login does not persist it.

The following code, therefore fails, but in a subtle way:

const client = sdk.createClient({ baseUrl: "https://matrix.org" });
await client.login("m.login.password", {
    identifier: { type: "m.id.user", user: "userid" },
    password: "mysecretpassword",
});
await client.initRustCrypto();

The normal usage of client.login() is to create a new MatrixClient based on the results, but if that is the intention:

1. The documentation should say so
2. It should not persist the access token either.

loginWithPassword and loginWithToken are similarly affected.