Laravel Sanctum return: Call to a member function createToken() on null

I am following sanctum documentation from here. I did all same as described but still it is not working.
I am getting an error when I am generating new token "Call to a member function createToken() on null".

use Illuminate\Http\Request;

Route::post('/tokens/create', function (Request $request) {
    $token = $request->user()->createToken($request->token_name);
 
    return ['token' => $token->plainTextToken];
});

Here is my code on github https://github.com/farukhaleem/sanctum

I am trying to use sanctum as it is described in the documentation. I am getting createToken() method for generating a token but I am unable to get anyting in $request->user(). I am using thunder client in vscode for getting result. http://127.0.0.1:8000/api/tokens/create is the endpoint, method type is POST. FORM data has token_name with value 'data'

The documentation assumes you have an authenticated user in your case you don't. this is why $request->user() is null.

So in order to just generate a token you could use the following

Route::post('/tokens/create', function (Request $request) {

    $user = User::find("some user id");
    $token = $user->createToken($request->token_name);
 
    return ['token' => $token->plainTextToken];
});

Since you are learning, it would make more sense if you transform your route into a log in with a form where the users can enter their email and password so on submit you generate the token.

Route::post('/login', function (Request $request) {

    # do any validations here

    $user = User::where('email', $request->email)->first();
    $token = $user->createToken("The user agent here");
 
    return ['token' => $token->plainTextToken];
});

Also note that on createToken it would be better if you pass the user agent. so you know the app that uses that specific token.