Channel argument treated as path

[MichaelXavier]

Description
The CLI documentation indicates that the first argument should be a channel name and the second a directory. However, if you have a channel name that happens to have the same name as a subdir of the current directory, tv will go against the documentation and treat the first argument as a dir, then it will run the default command, typically files

Example
I have the following channel for npins

# npins.toml
[metadata]
description = "A channel to select npins pins for update, freeze, or unfreeze"
name = "npins"
requirements = ["npins", "jq"]

[preview]
command = "jq '.pins[\"{}\"]' npins/sources.json"

[source]
command = "jq -r '.pins | keys[]' npins/sources.json"

When I run tv npins in my project root with an npins subdir, it selects the files channel and shows me the files in npins

Expected behavior
I would expect it would select the npins channel with no directory argument.

Environment

• OS: NixOS
• TV version: 0.15.4
• shell: fish
• terminal: wezterm

# config.toml
[ui]
theme = "catppuccin-mocha-mauve"
use_nerd_font_icons = true

Additional context
This is likely a regression introduced in e76a3df in cli/mod.rs. Previously it checked for the existence of a channel but that logic got flipped and it now checks if the first argument is a directory and only falls back to treating it as a channel if it isn't.