testScalarNA and data.table

R 4.2.2
data.table 1.14.8
checkmate 2.2.0

Hallo Michel,

using checkmate function `testScalarNA` on a data.table object returns the following warning:

    In length(x) != 1L || !is.na(x) :
      'length(x) = 2 > 1' in coercion to 'logical(1)'

Reproduction via:

    dt = data.table(x = 1:2)
    testScalarNA(dt)

Is this a bug or did I do something wrong?

All the best
Dirk