parameter_absent exception

I am using the Mautic library but getting the following error when making a call.

{"message":"Looks like I encountered an error (error #400). If I do it again, please report me to the system administrator!","code":400,"type":null}

The logs show the following:

[2020-11-17 08:38:09] mautic.ERROR: Uncaught PHP Exception Symfony\Component\HttpKernel\Exception\HttpException: "parameter_absent" at /home/my-mautic/public_html/vendor/willdurand/oauth-server-bundle/Service/OAuthServerService.php line 109 {"exception":"[object] (Symfony\\Component\\HttpKernel\\Exception\\HttpException(code: 0): parameter_absent at /home/my-mautic/public_html/vendor/willdurand/oauth-server-bundle/Service/OAuthServerService.php:109)"} []

Not sure what I am missing here. This is the code I am using as per the documentation:

$initAuth       = new ApiAuth();
$this->auth     = $initAuth->newAuth([
            'baseUrl'      => 'https://my-mautic-address.com/api',
            'version'      => 'OAuth1a',
            'clientKey'    => \Bin\Config::MAUTIC_CONSUMER_KEY,
            'clientSecret' => \Bin\Config::MAUTIC_CONSUMER_SECRET,
            'callback'     => \Bin\Config::MAUTIC_CALLBACK_URL
]);

$this->apiUrl   = "https://my-mautic-address.com/api";
$this->mautic   = new MauticApi();

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Start with the documented ApiAuth and newAuth configuration in the issue, then inspect OAuthServerService.php at line 109 and the surrounding OAuth request flow. Reproduce the call using the supplied baseUrl, OAuth1a settings, credentials, and callback, and compare the request with the parameter expected at that failure point. Done means identifying the missing or malformed parameter and documenting or fixing the failing API call.