After the recent update, it seems coverage no longer works on GPos objects? 

library(GenomicRanges)

## Example 2:
pos_runs <- GRanges("chrI", IRanges(c(1, 6, 12, 17), c(5, 10, 16, 20)),
                                        strand=c("+", "-", "-", "+"))
gpos2 <- GPos(pos_runs)

coverage(as(gpos2, "GRanges")) # works
coverage(gpos2) # error

Or is this no longer the proper way of calling coverage?