Fix overwrite option for copying directories

[bloeo]

Currently, the overwrite option when copying directories only works if the target already exists and is a directory. fs::remove_dir_all(target) errors if the target does not exist, and currently the overwriting code does not account for that whatever is overwritten might be a file rather than a directory.

fs = require("@lune/fs")

fs.writeDir("example")
fs.copy("example", "example2", {
    overwrite = true, -- If true, will error if a directory named "example2" doesn't already exist
})

[filiptibell]

Good catch - thank you for the fix! One small comment and this should be good to go.

Path::exists uses sync filesystem API under the hood, so we end up doing two filesystem reads one of which unexpectedly blocks the thread.
One call to fs::metadata should be enough and we can match on the NotFound error instead and ignore that. Similar to how we do here:

lune/src/lune/builtins/fs/copy.rs

Lines 103 to 112 in b75cc2a

	let (is_dir, is_file) = match fs::metadata(&source).await {
	Ok(meta) => (meta.is_dir(), meta.is_file()),
	Err(e) if e.kind() == ErrorKind::NotFound => {
	return Err(LuaError::RuntimeError(format!(
	"No file or directory exists at the path '{}'",
	source.display()
	)))
	}
	Err(e) => return Err(e.into()),
	};

[filiptibell]

LGTM