Ehancement: CLI - Better error message for invalid --app string

[henryruhs]

Description

A condition is missing for the case that app_path does not contain a colon.

Using Litestar app from env: 'invalid'
Traceback (most recent call last):
  File "/home/henry/miniconda3/envs/facefusion/bin/litestar", line 8, in <module>
    sys.exit(run_cli())
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/litestar/__main__.py", line 6, in run_cli
    litestar_group()
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/rich_click/rich_command.py", line 367, in __call__
    return super().__call__(*args, **kwargs)
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/rich_click/rich_command.py", line 151, in main
    with self.make_context(prog_name, args, **extra) as ctx:
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/litestar/cli/_utils.py", line 224, in make_context
    self._prepare(ctx)
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/litestar/cli/_utils.py", line 206, in _prepare
    env = ctx.obj = LitestarEnv.from_env(ctx.params.get("app_path"), ctx.params.get("app_dir"))
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/litestar/cli/_utils.py", line 112, in from_env
    loaded_app = _load_app_from_path(app_path)
  File "/home/henry/miniconda3/envs/facefusion/lib/python3.10/site-packages/litestar/cli/_utils.py", line 276, in _load_app_from_path
    module_path, app_name = app_path.split(":")
ValueError: not enough values to unpack (expected 2, got 1)

Either add a condition to _load_app_from_path or introduce a safe_split utility/helper.

URL to code causing the issue

No response

MCVE

litestar --app invalid

### Steps to reproduce

_No response_

### Screenshots

```bash
"![SCREENSHOT_DESCRIPTION](SCREENSHOT_LINK.png)"

Logs

No response

Litestar Version

2.13.0final0

Platform

• Linux
• Mac
• Windows
• Other (Please specify in the description above)

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[provinzkraut]

This isn't really a bug. You're passing in an invalid value and are presented with a ValueError, which I think is appropriate. I'm assuming you're looking for a better error message here?

[henryruhs]

Yeah, something like "Invalid argument passed" instead of an exception.