why mime.getType('unknown') returns null rather then 'application/octet-stream'

[xxoo]

according to https://tools.ietf.org/html/rfc2045

Any entity with an unrecognized Content-Transfer-Encoding must be
treated as if it has a Content-Type of "application/octet-stream",
regardless of what the Content-Type header field actually says.

as i understood a unknown file type should use application/octet-stream for sure.

[broofa]

This module is not an RFC-related module. It's a thin, optimized API for the mime-db dataset. That said, the previous version of this module had the behavior you described. However, this behavior was deemed undesirable (see #139).

Basically, returning null is what most people expect, and it's trivial for callers of this API to code a default value. E.g. var type = mime.getType(...) || 'application/octet-stream';.

[almercier]

@broofa This should have been documented as a breaking change as this broke our logic what was expecting the 'application/octet-stream' default return value.