Using sendResetLink get Trying to access array offset on value of type null

I´m trying to send email reset password and I´m getting error:

Trying to access array offset on value of type null

I´m doing:

$this->validateEmail($request);

$response = $this->broker()->sendResetLink(
    $request->only('email')
);

return $response == Password::RESET_LINK_SENT
    ? $this->sendResetLinkResponse($request, $response)
    : $this->sendResetLinkFailedResponse($request, $response);

When execute sendResetLink appears the error.. Any solution ?

Thanks

via Chebli Mohamed