Why Guzzle onrejected function in promise-then still throw an exception?

I found that the $promise->wait() function will throw an exception and I must use try-catch to handle exception again.

$promise = $this->client->sendAsync($request);
$promise->then(
    function ($response) use (...){
        //do something
    },
    function ($exception) {
        $this->logger->error("Failed " . $exception->getMessage());
    }
);
try{
    $promise->wait(true);
}catch(Exception $exception){
    $this->logger->error("Failed " . $exception->getMessage());
}

The error info will be recorded by logger twice. Is there any method that the exception can be handled in onrejected fuction? Or any better way to handle such exception?

Here’s my error:
PHP Fatal error: Uncaught GuzzleHttpExceptionClientException: Client error:…

Thank you very much for your help.

I have tried this

$promise->then(
//...
)->then(
//...
);

but not work.