The token in issueToken function always return null even though the body has its content

[eternalBlast]

Here is CustomerTokenAuthController@issueToken function

public function issueToken(ServerRequestInterface $request)
     {
         $body = (parent::issueToken($request)); // got the response header with its content of access and refresh tokens
         $token = json_decode($body, true); //return null
        
         if (array_key_exists('error', $token)) {
             return response()->json([
                 'error' => $token['error'],
                 'status_code' => 401
             ], 401);
         }
         
        $data = $request->getParsedBody();
        
        $email = $data['username'];  
           
        switch ($data['provider']) {
            case 'customers';
                
                try {
                
                 $user = Customer::where('username', $email)->firstOrFail();
                 
                } catch (ModelNotFoundException $e) {
                  return response()->json([
                      'error' => $e->getMessage(),
                      'status_code' => 401
                  ], 401);
                }
            
                break;
            
            default :
            
                try {
                
                 $user = User::where('email', $email)->firstOrFail();
                 
                } catch (ModelNotFoundException $e) {
                  return response()->json([
                      'error' => $e->getMessage(),
                      'status_code' => 401
                  ], 401);
                }        
        }

[eternalBlast]

Got a simple hack. But, the solution is not very elegant. At least, we can get the token object at the end.
These are the steps:

1. Convert $body toString.
   $body = (parent::issueToken($request))->__toString();

2. Manipulate the string by removing blank and /r characters, then retrieve position start of open curly brackets.

$res=preg_replace('/\s+/', '',$body);
$res = substr($res, strpos($res, "{"), strpos($res, "}")); //start from position of open curly bracket till the end of curly bracket , you can trim the third param if you want. It's just for semantic purpose. :) 
$token = json_decode( $res, true );

If someone can give a greater solution, maybe can post here.