Gary is encountering an 'undefined' error when trying to access `hubspotClient.files.filesApi` in a serverless function, suspecting it's due to an outdated version of the `@hubspot/api-client` used in the serverless environment.

Nicholas suggests this is likely the issue, acknowledging that the version of the `@hubspot/api-client` available in serverless functions might lag behind the latest npm version and differ from other environments like workflows, potentially causing inconsistencies.