Identify the missing file in the 404 message

[ScottHuston]

I sent a request with a typo in one of the 11 externalScripts.urls

I got a 400 Bad Request with

{
    "error": "Failed to download file: Failed to download file: HTTP 404 - Not Found"
}

Which was the missing file?

downloader\FileDownloader.java

~line:116

            throw new IOException(
                    "Failed to download file: "
                            + fileUrl
                            + " - HTTP " + connection.getResponseCode()
                            + " - "
                            + connection.getResponseMessage());

There's also an opportunity to identify the file ~line 98 in a different IOException