`!` combined with a logical call in `j` seem to have precedence bug

[DavidArenburg]

Reproducible example

library(data.table) #v1.11.2
dt <- data.table(a = 1, b = NA)
dt[, !is.na(dt), with = FALSE]
#    a
# 1: 1

dt <- data.table(a = 1, b = 2)
dt[, !is.na(dt), with = FALSE]
## Null data.table (0 rows and 0 cols)

## Should be
#    a b
# 1: 1 2

Source on SO

I've investigated this and seem to found the bug. I would guess it is a relatively easy fix.