column type 'expression' not supported by data.table subset

[tsp]

The example below produces the following error:
Error in [.data.table(data.table(a = 1, b = expression(1)), , b, by = a) :
Internal error: column type 'expression' not supported by data.table subset. All known types are supported so please report as bug.

# Minimal reproducible example
data.table(a=1,b=expression(1))[,b,by=a]

# Output of sessionInfo()
R version 4.2.2 (2022-10-31 ucrt)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19044)

Matrix products: default

locale:
[1] LC_COLLATE=Danish_Denmark.utf8 LC_CTYPE=Danish_Denmark.utf8 LC_MONETARY=Danish_Denmark.utf8 LC_NUMERIC=C LC_TIME=Danish_Denmark.utf8

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] data.table_1.14.6

loaded via a namespace (and not attached):
[1] compiler_4.2.2 tools_4.2.2 rstudioapi_0.14

[ben-schwen]

Ty for the hint. Actually, your example covers two cases:

1. data.table is not able to subset expression columns
2. group evaluation via dogroups does not work with expression columns