Bug Description
Instead of returning listings from a specific SteamID64, the user_id query parameter falls back to the default GET response that would be received if no query parameters were provided (first 50 listings). This occurs with both users that have no active listings and users with active listings.
Screenshots
Browser request (Windows 11, Firefox 151.0)

Curl request (Version 8.18.0)

Bug Description
Instead of returning listings from a specific SteamID64, the user_id query parameter falls back to the default GET response that would be received if no query parameters were provided (first 50 listings). This occurs with both users that have no active listings and users with active listings.
Screenshots


Browser request (Windows 11, Firefox 151.0)
Curl request (Version 8.18.0)