Print Methods Subscript Out of Bounds

[brodieG]

Ticks: 2866; Iterations: 4; Time Per: 1.537 seconds; Time Total: 6.149 seconds; Time Ticks: 2.866Error in y[[2]] : subscript out of bounds

Must be because in this code:

26: is_strictly_numeric(upper)
25: between(x, y[[1]], y[[2]], incbounds = TRUE)
24: level %between% c(en.lvl, ex.lvl)
23: eval(expr, envir, enclos)
22: eval(.massagei(isub), x, parent.frame())
21: `[.data.table`(x.cp[children], level %between% c(en.lvl, ex.lvl), 
        sum(n.self))
20: x.cp[children][level %between% c(en.lvl, ex.lvl), sum(n.self)]
19: collapse_passthru_fun(x.new, i)
18: collapse_passthru_funs(x.new)

one of en.lvl or ex.lvl gets set to NULL.