If we call file:sendfile/2 directly we don't close the file inside a try/catch, are vulnerable to #39 and have default of 20MB chunk size. I am happy to call file:sendfile/2 directly but file:sendfile/2 calls file:sendfile/5 anyway so I'm unsure there is a saving here once I resolve the later two of the three I mentioned. As file:sendfile/2 does not ensure the file is closed shall I remove the try/catches for opening?

Ps: Thanks for thorough review, must have taken some time.