Slim API returns error only with AJAX request

Question

Hello, I developed an API using the Slim Framework and testing one of the endpoints that with Postman works perfectly but when I request with AJAX, although it is sending exactly the same data that I send with Postman it seems that the data does not arrive correctly and I do not know why it happens.

Request no Postman:

AJAX function:

function ajaxRequest(verb, endpoint, headers = null, body = null) {
    try {
        //Animação do loading
        $('.container').waitMe({
            effect: 'facebook'
        });

        var resp = null;

        $.ajax({
            url: 'http://localhost/projetos/soccerama/api/' + endpoint,
            type: verb,
            ContentType: 'application/json',
            async: false,
            headers: {
                'xAuthChaveApi': localStorage.xAuthChaveApi,
                'xAuthCambistaID': localStorage.xAuthCambistaID,
                'xAuthCambistaToken': localStorage.xAuthCambistaToken
            },
            success: function(response) {
                resp = response
            },
            error: function(error) {
                notificar(Status.SERVER_ERR);
            },
            beforeSend: function(xhr) {
                if(headers !== null) {
                    for(var key in headers) {
                        xhr.setRequestHeader(key, headers[key]);
                    }
                }
            }
        });
    } catch (error) {
        notificar(error);
    } finally {
        $('.container').waitMe('hide');
        return resp;
    }

}

Calling the ajax function in the authentication function:

function autenticar() {
    var usuario = $('#inputUsuario').val();
    var senha = $('#inputSenha').val();
    var pin = $('#inputPin').val();

    if(!usuario || !senha || !pin) {
        notificar('Ops! Tem algo errado, tem certeza que digitou o seu usuário, senha e PIN corretamente?');
        return null;
    }

    //Declarando os headers
    var headers = {
        usuario: usuario,
        senha: senha,
    }

    var cambista = ajaxRequest(Verb.GET, Endpoint.AUTH_CAMBISTA, headers);    
}

Request data collected from browser:

Request URL:http://localhost/projetos/soccerama/api/cambista/autenticar
Request Method:GET
Status Code:200 OK
Remote Address:[::1]:80
Referrer Policy:no-referrer-when-downgrade

Response Headers
view source
Connection:Keep-Alive
Content-Length:315
Content-Type:application/json;charset=utf-8
Date:Fri, 03 Nov 2017 16:04:59 GMT
Keep-Alive:timeout=5, max=100
Server:Apache/2.4.28 (Unix) OpenSSL/1.0.2l PHP/7.1.10 mod_perl/2.0.8-dev Perl/v5.16.3
X-Powered-By:PHP/7.1.10

Request Headers
view source
Accept:*/*
Accept-Encoding:gzip, deflate, br
Accept-Language:pt-BR,pt;q=0.9,en-US;q=0.8,en;q=0.7
Connection:keep-alive
Host:localhost
Referer:http://localhost/projetos/soccerama/mobile/www/login.html
senha:teste
User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36
usuario:admin
X-Requested-With:XMLHttpRequest
xAuthChaveApi:3851b1ae73ca0ca6e3c24a0256a80ace

Browser response:

{
   "meta":{
      "status":"warning",
      "message":"Um erro ocorreu ao executar a opera\u00e7\u00e3o. Tente 
      novamente ou entre em contato com o administrador."
   }
}
Notice:  Undefined variable: cambista in /opt/lampp/htdocs/projetos/soccerama/api/app/controllers/CambistaController.php on line 168

API method:

public static function autenticar(Request $request, Response $response) {
        try {
            $credenciais = array(
                'login' => (array_key_exists(0, $request->getHeader('login')) ? $request->getHeader('login')[0] : null),
                'senha' => (array_key_exists(0, $request->getHeader('senha')) ? md5(SALT . $request->getHeader('senha')[0]) : null)
            );

            if ( isset($credenciais['login']) && isset($credenciais['senha']) ) {
                $cambista = Cambista::where($credenciais)
                    ->get()
                    ->first();

                if (isset($cambista)) {
                    $cambista->sessao = new Sessao();
                    $cambista->sessao->idCambista = $cambista->id;
                    $cambista->sessao->token = md5(uniqid(rand(), true));
                    $cambista->sessao->save();

                    $cambista = cambista::where('id', $cambista->id)
                        ->with('telefones')
                        ->with('regional')
                        ->with([
                            'sessao' => function($query) {
                                $query->orderBy('criado', 'DESC')->take(1);
                            }
                        ])
                        ->get()
                        ->first();

                    $meta = Helper::metaArray(Enum::SUCS_STS, Enum::AUTHORIZED);
                } else {
                    $meta = Helper::metaArray(Enum::WARN_STS, Enum::LOGIN_ERROR);
                }
            } else {
                $meta = Helper::metaArray(Enum::WARN_STS, Enum::INTERNAL_ERROR);
            }

            return $response->withCustomJson($meta, $cambista);
        } catch (Exception $ex) {
            $meta = Helper::metaArray(Enum::ERR_STS, Helper::exceptionError($ex), 400);

            return $response->withCustomJson($meta);
        }
    }