BrowserClient with outh2 config wields empty client_id and redirect_uri query parameters

Consider the following code:

const oauth2 = new jsforce.OAuth2({
      clientId: 'some-client-id',
      redirectUri: 'some-redirect-uri',
});
const client = new jsforce.BrowserClient();
client.init({
    oauth2: oauth2
} as any);
client.login();

This code opens a popup with:
Actual Authorization URL: https://login.salesforce.com/services/oauth2/authorize?response_type=code&state=jsforce10.popup.krxv9lgkg3n&client_id=&redirect_uri=
Expected Authorization URL: https://login.salesforce.com/services/oauth2/authorize?response_type=code&state=jsforce10.popup.krxv9lgkg3n&client_id=some-client-id&redirect_uri=some-redirect-uri

If I change the above code (note I need to force the config object to any since this does not match the types.

const client = new jsforce.BrowserClient();
client.init({
      clientId: 'some-client-id',
      redirectUri: 'some-redirect-uri',
} as any);
client.login();

Then, the expected URL is generated. But this is not matching the typescript types.

Start at BrowserClient.init and login, then trace how the supplied OAuth2 instance is read when building the authorization URL. Compare that path with the direct clientId and redirectUri configuration path; done means the typed OAuth2 configuration produces the expected non-empty parameters and accepts the shown TypeScript usage.