When limit field in range(options) is omitted or set to null a default value of 10 is set in index.js line 12
I am not sure if this is intentional or not, but it's not accurately reflected in the documentation:
options.limit - optional If range not specified in the request, range 0-(limit-1) is assumed
In any case there should be a way to avoid setting a default limit, so that req.range gets a non-null value only if the HTTP client sent a Range header.