[BUG] nvflare provision doesn't exit with a code >0 on input validation errors

[ferrarimarco]

Describe the bug

Running nvflare provision against a project.yml that doesn't pass argument checks returns a 0 exit code, making it impossible to reliably use the nvflare provision command in scripts, unless the script parses nvflare provision output.

To Reproduce

Steps to reproduce the behavior:

1. Create a project.yml with the following contents:

api_version: 3
name: example_project
description: NVIDIA FLARE sample project yaml file

participants:
  - name: server1.nvidia-flare-example.com
    type: server
    org: nvidia
    fed_learn_port: 8002
    admin_port: 8003
  # The following line fails validation
  - name: client1.example.com
    type: client
    org: nvidia
  - name: [email protected]
    type: admin
    org: nvidia
    role: project_admin

builders:
  - path: nvflare.lighter.impl.workspace.WorkspaceBuilder
    args:
      template_file: master_template.yml
  - path: nvflare.lighter.impl.template.TemplateBuilder
  - path: nvflare.lighter.impl.static_file.StaticFileBuilder
    args:
      config_folder: config
      overseer_agent:
        path: nvflare.ha.dummy_overseer_agent.DummyOverseerAgent
        overseer_exists: false
        args:
          sp_end_point: server1:8002:8003

  - path: nvflare.lighter.impl.cert.CertBuilder
  - path: nvflare.lighter.impl.signature.SignatureBuilder

1. Run nvflare provision

2. Observe the output:

Unable to handle command: provision due to: name=client1.nvidia-flare-example.com is ill-formatted based on regex_pattern=^[A-Za-z0-9-_]+$ 

sub_parser is: ArgumentParser(prog='nvflare provision', usage=None, description=None, formatter_class=<class 'argparse.HelpFormatter'>, conflict_handler='error', add_help=True)
usage: nvflare provision [-h] [-p PROJECT_FILE] [-w WORKSPACE] [-c CUSTOM_FOLDER] [--add_user ADD_USER] [--add_client ADD_CLIENT]

optional arguments:
  -h, --help            show this help message and exit
  -p PROJECT_FILE, --project_file PROJECT_FILE
                        file to describe FL project
  -w WORKSPACE, --workspace WORKSPACE
                        directory used by provision
  -c CUSTOM_FOLDER, --custom_folder CUSTOM_FOLDER
                        additional folder to load python codes
  --add_user ADD_USER   yaml file for added user
  --add_client ADD_CLIENT
                        yaml file for added client

1. Get the exit code:

echo $?

1. Observe the output:

0

Expected behavior

nvflare provision should return a non-zero exit code on validation errors.

Environment (please complete the following information):

Reproducible using the nvflare docker image: nvflare/nvflare:2.4.2