file_not_found.lean:6:0-6:77: error: no such file or directory (error code: 2)
  file: non-existent-file.txt


file_not_found.lean:13:0-13:69: error: permission denied (error code: 13)
  file: readonly.txt

file_not_found.lean:14:0-18:9: error: invalid argument (error code: 9, bad file descriptor)