src/Horizon/Api/HorizonResponse.php
public function mustGetField($fieldName)
    {
        if (!isset($this->rawData[$fieldName])) throw new \InvalidArgumentException(sprintf("Field '%s' not present in response", $fieldName));

        return $this->rawData[$fieldName];
    }
public function mustGetField($fieldName)
    {
        if (!isset($this->rawData[$fieldName])) throw new \InvalidArgumentException(sprintf("Field '%s' not present in response", $fieldName));

        return $this->rawData[$fieldName];
    }
Throws an exception if $fieldName is not present in the response

@param $fieldName
@throws \InvalidArgumentException
@return mixed|null