[Bug]: KeyError: 'default'

[MHendricks]

Summary

Provide easier to understand feedback when running into this error. This happens when there is no default config found.

Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Program Files\Python39\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Program Files\Python39\lib\site-packages\hab\__main__.py", line 14, in <module>
    sys.exit(hab.cli.cli(prog_name="python -m hab"))
  File "C:\Program Files\Python39\lib\site-packages\hab\cli.py", line 425, in cli
    return _cli(*args, **kwargs)
  File "C:\Program Files\Python39\lib\site-packages\click\core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
  File "C:\Program Files\Python39\lib\site-packages\click\core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "C:\Program Files\Python39\lib\site-packages\click\core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "C:\Program Files\Python39\lib\site-packages\click\core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "C:\Program Files\Python39\lib\site-packages\click\core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "C:\Program Files\Python39\lib\site-packages\click\decorators.py", line 38, in new_func
    return f(get_current_context().obj, *args, **kwargs)
  File "C:\Program Files\Python39\lib\site-packages\hab\cli.py", line 414, in launch
    settings.write_script(
  File "C:\Program Files\Python39\lib\site-packages\hab\cli.py", line 111, in write_script
    ret = self.resolver.resolve(uri)
  File "C:\Program Files\Python39\lib\site-packages\hab\__init__.py", line 268, in resolve
    context = self.closest_config(uri)
  File "C:\Program Files\Python39\lib\site-packages\hab\__init__.py", line 123, in closest_config
    return self.closest_config(path, default=True)
  File "C:\Program Files\Python39\lib\site-packages\hab\__init__.py", line 103, in closest_config
    current = self.configs["default"]
KeyError: 'default'

Expected Behavior

.

Steps to Reproduce Behavior

Setup a hab environment that doesn't have a default configuration.

Solution

Make this return a descriptive error message indicating that there was no default configuration to use so it couldn't resolve the uri.

Environment

Hab==0.16.0

Additional Context

.