If the standard output of the current R process is not a terminal, e.g. because it is redirected to a file, or the R process is running in a GUI, then it will throw an error. You need to handle this error if you want to use this function in a package.
Details
If an error happens, the error message is different depending on what type of device the standard output is. Some common error messages are:
"Inappropriate ioctl for device."
"Operation not supported on socket."
"Operation not supported by device."
Whatever the error message, ps_tty_size
always fails with an error of
class ps_unknown_tty_size
, which you can catch.