Good catch. I've fixed it and pushed.

Ironically, this is essentially an error I've corrected many times in others' R code.  People would attempt to create a sequence of indices and not account for the case when the vector is null.  It's so common, R has multiple helper-function solutions. Here's one. Is there something equivalent in CoffeeScript?

x <- NULL

#wrong. This actually makes the loop executes twice.
sapply(1:length(x),
       nchar)

#correct
sapply(seq_along(x),
       nchar)