title: php-open-source-saver/jwt-auth login error
body: <p>i get the following error when i try to login and i don't find where the problem is. I use lumen 9 with php 8.1.</p>
  <pre><code>&lt;!-- Lcobucci\JWT\Token\Builder::relatedTo(): Argument #1 ($subject) must be of type string, null given, called in /home/ss20nt22/public_html/wms/vendor/php-open-source-saver/jwt-auth/src/Providers/JWT/Lcobucci.php on line 212 (500 Internal Server Error) --&gt;
  </code></pre>
  <p>here is my function:</p>
  <pre><code>public function login(Request $request)
      {
          
          $this-&gt;validate($request, [
              'nume' =&gt; 'required|string',
              'password' =&gt; 'required|string',
          ]);
          $credentials = $request-&gt;only(['nume', 'password']);
          if (!$token = Auth::attempt($credentials)) {
              // Login has failed
              return response()-&gt;json(['message' =&gt; 'Unauthorized'], 401);
          }
          return $this-&gt;respondWithToken($token);
      }
  </code></pre>