Node WPAPI REST with JWT Authentication combined?

Question

I have a Wordpress REST-API Backend with a UI5 JavaScript Frontend which loads some Post-Data to list them.

I want to protect this by a simple Login-Form in the Frontend.

To fetch and create the posts i use Node-WPAPI with basic authencation, like this:

this._oWp = new WPAPI({
    endpoint: 'http://<domain>/wordpress/wp-json',
    username: '<user>',
    password: '<pass>'
});

But this approach dont fit my needs, because creating this WPAPI instance is even possible with a wrog password. Thus i would have to send a request to protected route first to know if my password was correct.

To directly know if my login was correct my idea was to firstly get a Token via "JWT Authentication for WP-API" and this actually works and i get the token.

But doing this my WPAPI Endpoints resulting with error "jwt_auth_bad_auth_header, "Authorization header malformed."

Is there a way to use WPAPI together with JWT Auth? Or how could a Login be authenticated by WPAPI Instance and get directly notified when the login credential were wrong?