It may not always be clear whether the path for the new proj is the actual proj dir, or the parent dir that the new proj dir will live in.
If we check that the dir is empty, it makes it less likely that they have accidentally chosen the parent dir.
Also, should consider whether if the dir does not exist but the parent does, the user may want to create it (for the command line args, probably not the dialogue)
It may not always be clear whether the path for the new proj is the actual proj dir, or the parent dir that the new proj dir will live in.
If we check that the dir is empty, it makes it less likely that they have accidentally chosen the parent dir.
Also, should consider whether if the dir does not exist but the parent does, the user may want to create it (for the command line args, probably not the dialogue)