How do I catch an exception in the Quickbooks PHP SDK OAuth2LoginHelper?

I'm trying to connect my custom PHP application with QuickBooks Online. I'm using their SDK at https://github.com/intuit/QuickBooks-V3-PHP-SDK. But this code will throw an exception if I have a bad token:

    try {
        // Refresh the token
        $OAuth2LoginHelper = $dataService->getOAuth2LoginHelper();
        $refresh = $accessToken->getRefreshToken();
        $accessTokenObj = $OAuth2LoginHelper->refreshAccessTokenWithRefreshToken($refresh);
        $accessTokenObj->setRealmID($currentServiceContext->realmId);
        $dataService->updateOAuth2Token($accessTokenObj);
        $_SESSION['sessionAccessToken'] = serialize($accessTokenObj);
    } catch (Exception $e) {
        print_r($e);
    }

Perhaps my PHP knowledge has a hole, but I thought a try{}catch(){} should stop the exception from shutting down my whole application. In this case, the try catch does nothing. The whole system halts to a white page instead and i have an exception listed in my error log.

Obviously, I need to be able to test if the token is good or bad and notify the user to reconnect quickbooks without shutting down the entire app.

What am I missing?

Relevant Error:

    "class": "QuickBooksOnline\\API\\Exception\\ServiceException",
    "message": "Refresh OAuth 2 Access token with Refresh Token failed. Body: [{\"error\":\"invalid_grant\"}].",
    "code": 400,
    "file": "/var/www/html/vendor/quickbooks/v3-php-sdk/src/Core/OAuth/OAuth2/OAuth2LoginHelper.php:309",
    "trace": [
        "/var/www/html/config.php:274",
        "/var/www/html/index.php:2"
    ]

And here's the function in the QBO PHP SDK:

    /**
     * Get a new access token based on the refresh token. Static function to make easy refreshToken API call.
     * @return OAuth2AccessToken     A new OAuth2AccessToken that contains all the information(accessTokenkey, RefreshTokenKey, ClientID, and ClientSecret, Expiration Time, etc)
     */
    public function refreshAccessTokenWithRefreshToken($refreshToken){
       $http_header = $this->constructRefreshTokenHeader();
       $requestBody = $this->constructRefreshTokenBody($refreshToken);
       $this->LogAPIRequestToLog($requestBody, CoreConstants::OAUTH2_TOKEN_ENDPOINT_URL, $http_header);
       $intuitResponse = $this->curlHttpClient->makeAPICall(CoreConstants::OAUTH2_TOKEN_ENDPOINT_URL, CoreConstants::HTTP_POST, $http_header, $requestBody, null, true);
       $this->LogAPIResponseToLog($intuitResponse->getBody(), CoreConstants::OAUTH2_TOKEN_ENDPOINT_URL, $intuitResponse->getHeaders());
       $this->faultHandler = $intuitResponse->getFaultHandler();
       if($this->faultHandler) {
          throw new ServiceException("Refresh OAuth 2 Access token with Refresh Token failed. Body: [" . $this->faultHandler->getResponseBody() . "].", $this->faultHandler->getHttpStatusCode());
       }else{
          $this->faultHandler = false;
          $this->oauth2AccessToken = $this->parseNewAccessTokenFromResponse($intuitResponse->getBody());
          return $this->getAccessToken();
       }
    }

This is line 309: throw new ServiceException("Refresh OAuth 2 Access token with Refresh Token failed. Body: [" . $this->faultHandler->getResponseBody() . "].", $this->faultHandler->getHttpStatusCode());

Sometimes I just gotta write it all out to figure it out.

I see it now. It's not an Exception, it's a ServiceException. So I needed that in my try catch, as follows:

    try {
        // Refresh the token
        $OAuth2LoginHelper = $dataService->getOAuth2LoginHelper();
        $refresh = $accessToken->getRefreshToken();
        $accessTokenObj = $OAuth2LoginHelper->refreshAccessTokenWithRefreshToken($refresh);
        $accessTokenObj->setRealmID($currentServiceContext->realmId);
        $dataService->updateOAuth2Token($accessTokenObj);
        $_SESSION['sessionAccessToken'] = serialize($accessTokenObj);
    } catch (ServiceException $e) {
        echo "Error: " . $e->getMessage();
    }