process.md
In processx: Execute and Control System Processes

non existing process

Code
  process$new(tempfile())
Condition
  Error:
  ! ! Native call to `processx_exec` failed
  Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:162:3:
  ! Command '<tempdir>/<tempfile>' not found @win/processx.c:982 (processx_exec)

working directory does not exist

Code
  process$new(px, wd = tempfile())
Condition
  Error:
  ! ! Native call to `processx_exec` failed
  Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:162:3:
  ! create process '<path>/px' (system error 267, The directory name is invalid.
  ) @win/processx.c:1040 (processx_exec)