Installation warning

[tetomonti]

When installing:
devtools::install_github("montilab/CaDrA",ref="dev")

Or loading:
library(CaDrA)

I get the following warning (on my Mac):

Warning in fun(libname, pkgname) :
  couldn't connect to display "/private/tmp/com.apple.launchd.ArCZPD0Xid/org.macosforge.xquartz:0"

Or this (on SCC):

Warning message:
  In fun(libname, pkgname) : couldn't connect to display ":0"

[katgit]

This is related to the UID value on Macs and Linux system. See : https://stackoverflow.com/questions/30599326/warning-message-during-building-an-r-package-invalid-uid-value-replaced-by-that

I am exploring if there is a way to avoid, but this warning does not occur on Windows and also is not "counted" toward the number of warnings during the package's check/build process.