colourpicker conflicts with parallel::makeCluster()

[jzhangc]

parallel::makeCluster(type = "FORK") will fail once colourpicker is attached.
library(colourpicker)
library(parallel)
cl <- makeCluster(10, type = "FORK")

Error in makeForkCluster(nnodes = spec, ...) : Cluster setup failed.
In addition: Warning message:
In socketAccept(socket = socket, blocking = TRUE, open = "a+b", :
problem in accepting connections on this socket

Sessioninfo :
R version 4.0.5 (2021-03-31)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Big Sur 10.16

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8

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

other attached packages:
[1] colourpicker_1.1.0

loaded via a namespace (and not attached):
[1] Rcpp_1.0.6 digest_0.6.27 later_1.2.0 mime_0.10 R6_2.5.0 lifecycle_1.0.0
[7] xtable_1.8-4 magrittr_2.0.1 rlang_0.4.11 miniUI_0.1.1.1 promises_1.2.0.1 ellipsis_0.3.2
[13] tools_4.0.5 htmlwidgets_1.5.3 shiny_1.6.0 fastmap_1.1.0 httpuv_1.6.1 compiler_4.0.5
[19] htmltools_0.5.1.1

[jzhangc]

seems it is an issue with the "later" package (shiny dependent)