chore: only attempt to load config from file if it exists (#18)

fixes #5

src/config.rs

@@ -30,27 +30,25 @@ pub fn config_path() -> Result<PathBuf, S2CliError> {
 }
 
 pub fn load_config(path: &Path) -> Result<S2Config, S2ConfigError> {
-    Config::builder()
-        .add_source(config::File::new(
+    let mut builder = Config::builder().add_source(config::Environment::with_prefix("S2"));
+    if path.exists() {
+        builder = builder.add_source(config::File::new(
             path.to_str().expect("config path is valid utf8"),
             FileFormat::Toml,
-        ))
-        .add_source(config::Environment::with_prefix("S2"))
-        .build()
-        .map_err(|_| S2ConfigError::LoadError)?
-        .try_deserialize::<S2Config>()
-        .map_err(|_| S2ConfigError::LoadError)
+        ));
+    }
+    Ok(builder.build()?.try_deserialize::<S2Config>()?)
 }
 
 pub fn create_config(config_path: &PathBuf, auth_token: String) -> Result<(), S2ConfigError> {
     let cfg = S2Config { auth_token };
 
     if let Some(parent) = config_path.parent() {
-        std::fs::create_dir_all(parent).map_err(|_| S2ConfigError::WriteError)?;
+        std::fs::create_dir_all(parent).map_err(S2ConfigError::WriteError)?;
     }
 
     let toml = toml::to_string(&cfg).unwrap();
-    std::fs::write(config_path, toml).map_err(|_| S2ConfigError::WriteError)?;
+    std::fs::write(config_path, toml).map_err(S2ConfigError::WriteError)?;
 
     Ok(())
 }
@@ -64,8 +62,8 @@ pub enum S2ConfigError {
     #[diagnostic(help(
         "Did you run `s2-cli config set`? or use `S2_AUTH_TOKEN` environment variable."
     ))]
-    LoadError,
+    LoadError(#[from] config::ConfigError),
 
     #[error("Failed to write config file")]
-    WriteError,
+    WriteError(#[source] std::io::Error),
 }