Feature request: check for effect-free functions called without assignment

[LilithHafner]

Motivating example: https://github.com/JuliaPy/PythonCall.jl/pull/386/files

julia> Base.infer_effects(ArgumentError, Tuple{String})
(+c,+e,+n,+t,+s,+m,+i)

Effect-free statements triggered for precompilation or benchmarking may be false positives.