fix: improve gh errors (#35)

If i force `gh` to be unavailable
```sh
λ ~/thisisarepo ❯ PATH="" ./target/debug/github-lsp
Error: NoToken
```

and if I'm not in a repo
```sh
λ ~/notarepo ❯ github-lsp
Error: NoOwner
```

It is hard to make it fail UTF8, but if it ever happens, it will say
```sh
Error: NotUTF8
```

src/gh/mod.rs

@@ -9,15 +9,19 @@ use tokio::process::Command;
 
 #[derive(Debug)]
 pub enum GitHubCLIError {
+    NoRepo,
     NoToken,
     NoOwner,
+    NotUTF8,
 }
 impl std::error::Error for GitHubCLIError {}
 impl fmt::Display for GitHubCLIError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             GitHubCLIError::NoOwner => write!(f, "No Owner found"),
             GitHubCLIError::NoToken => write!(f, "No Token found"),
+            GitHubCLIError::NotUTF8 => write!(f, "No valid UTF-8 found"),
+            GitHubCLIError::NoRepo => write!(f, "No gh repo found"),
         }
     }
 }
@@ -39,7 +43,7 @@ async fn gh_cli_token() -> Result<String, GitHubCLIError> {
         .stdout
         .to_owned();
     let output = String::from_utf8(output)
-        .map_err(|_| GitHubCLIError::NoToken)?
+        .map_err(|_| GitHubCLIError::NotUTF8)?
         .trim()
         .to_owned();
     Ok(output)
@@ -55,11 +59,11 @@ pub async fn gh_cli_owner_name() -> std::result::Result<(String, String), GitHub
         .arg(".owner.login,.name")
         .output()
         .await
-        .map_err(|_| GitHubCLIError::NoOwner)?
+        .map_err(|_| GitHubCLIError::NoRepo)?
         .stdout
         .to_owned();
     String::from_utf8(output)
-        .map_err(|_| GitHubCLIError::NoOwner)?
+        .map_err(|_| GitHubCLIError::NotUTF8)?
         .trim()
         .split_once('\n')
         .map(|on| (on.0.to_string(), on.1.to_string()))