There's a lot of overlap between file extensions and TLDs though. .py, .sh, and .app are some more examples (but a fully exhaustive list would be in the dozens if not hundreds). At some point you have to just treat them as the separate namespaces that they actually are (and not somehow try to block a TLD from being used as a file extension, or vice-versa).

Besides, accidentally resolving a file extension to a TLD is only one of many possible different serious errors that can result from exposing an API that can load files locally or remotely, and thus make network calls that you might not be expecting. Fundamentally you need to fix that API either way.