R help - Dec 2019 - safest way to subset (and replace) a data.table

Hi

I would like to replace a data.table 'DT' with a subset of itself, where
the subset is determined by an expression 'expr' which evaluates to 
logical. Thus far I've been using:

 ?? DT <- DT[expr, ]

however this frequently results in a SIGABRT from glibc of the form:

 ?? "double free or corruption (!prev): 0x00000000c08662b40"

I've tried under the latest version of R and the latest version of data 
table, but the issue still persists. So now I'm wondering if I'm doing 
it the wrong way.

Any advice?

Regards

Ben