$ dynaconf get DONTEXIST
Traceback (most recent call last):
  File "/venv/bin/dynaconf", line 8, in <module>
    sys.exit(main())
  File "/src/dynaconf/dynaconf/vendor/click/core.py", line 857, in __call__
    return self.main(*args, **kwargs)
  File "/src/dynaconf/dynaconf/vendor/click/core.py", line 810, in main
    rv = self.invoke(ctx)
  File "/src/dynaconf/dynaconf/vendor/click/core.py", line 1292, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/src/dynaconf/dynaconf/vendor/click/core.py", line 1099, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/src/dynaconf/dynaconf/vendor/click/core.py", line 613, in invoke
    return callback(*args, **kwargs)
  File "/src/dynaconf/dynaconf/cli.py", line 476, in get
    result = settings[key]  # let the keyerror raises
  File "/src/dynaconf/dynaconf/utils/functional.py", line 19, in inner
    return func(self._wrapped, *args)
  File "/src/dynaconf/dynaconf/base.py", line 315, in __getitem__
    raise KeyError(f"{item} does not exist")
KeyError: 'DONTEXIST does not exist'

$ dynaconf get DONTEXIST
Key not found.  # stderr
$ echo $?   # proper retcode
1

$ dynaconf list -k DONTEXIST
Django app detected
Working in development environment 
Key not found