Better Error Handling for ValueError: invalid literal for int() with base 10: 'None'

[iporollo]

Description

Seeing an error when running the application locally with flask run

 flask run
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
Traceback (most recent call last):
  File "/Users/ivanporollo/Desktop/monosi/.venv/bin/flask", line 33, in <module>
    sys.exit(load_entry_point('Flask==2.0.2', 'console_scripts', 'flask')())
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 994, in main
    cli.main(args=sys.argv[1:])
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 600, in main
    return super().main(*args, **kwargs)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/click-8.0.4-py3.9.egg/click/core.py", line 1053, in main
    rv = self.invoke(ctx)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/click-8.0.4-py3.9.egg/click/core.py", line 1659, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/click-8.0.4-py3.9.egg/click/core.py", line 1395, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/click-8.0.4-py3.9.egg/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/click-8.0.4-py3.9.egg/click/decorators.py", line 84, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/click-8.0.4-py3.9.egg/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 849, in run_command
    app = DispatchingApp(info.load_app, use_eager_loading=eager_loading)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 324, in __init__
    self._load_unlocked()
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 350, in _load_unlocked
    self._app = rv = self.loader()
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 410, in load_app
    app = locate_app(self, import_name, None, raise_if_not_found=False)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/Flask-2.0.2-py3.9.egg/flask/cli.py", line 260, in locate_app
    __import__(module_name)
  File "/Users/ivanporollo/Desktop/monosi/src/server/__init__.py", line 10, in <module>
    from server.middleware import middleware
  File "/Users/ivanporollo/Desktop/monosi/src/server/middleware/__init__.py", line 3, in <module>
    from .scheduler import init_scheduler
  File "/Users/ivanporollo/Desktop/monosi/src/server/middleware/scheduler.py", line 4, in <module>
    from server.config import Config
  File "/Users/ivanporollo/Desktop/monosi/src/server/config.py", line 22, in <module>
    class BaseConfig:
  File "/Users/ivanporollo/Desktop/monosi/src/server/config.py", line 36, in BaseConfig
    SCHEDULER_JOBSTORES = {"default": SQLAlchemyJobStore(url=SQLALCHEMY_DATABASE_URI, tablename="msi_jobs")}
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/APScheduler-3.9.1-py3.9.egg/apscheduler/jobstores/sqlalchemy.py", line 52, in __init__
    self.engine = create_engine(url, **(engine_options or {}))
  File "<string>", line 2, in create_engine
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/sqlalchemy/util/deprecations.py", line 309, in warned
    return fn(*args, **kwargs)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/sqlalchemy/engine/create.py", line 530, in create_engine
    u = _url.make_url(url)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/sqlalchemy/engine/url.py", line 715, in make_url
    return _parse_rfc1738_args(name_or_url)
  File "/Users/ivanporollo/Desktop/monosi/.venv/lib/python3.9/site-packages/sqlalchemy/engine/url.py", line 771, in _parse_rfc1738_args
    components["port"] = int(components["port"])
ValueError: invalid literal for int() with base 10: 'None'

Expected behavior

This error occurs because local environment variables have not been set for the Monosi database. To solve this error, you need to set the following environment variables in the shell:

export DB_USER=<USER>
export DB_PASSWORD=<PASSWORD>
export DB_HOST=<HOST>
export DB_PORT=<PORT>
export DB_DATABASE=<DATABASE>
export DB_SCHEMA=<SCHEMA>

There should be better error handling to notify the user that their environment variables have not been set.

Steps to reproduce

1. Clone the monosi repository
2. Follow the monosi setup instructions for local environment
3. Run the server through flask run
4. Observe error