feat: improve error message

when init config failed:

```
Error: init config failed

Caused by:
    0: internal server error read ./config.toml failed
    1: read ./config.toml failed
    2: No such file or directory (os error 2)
```

src/config.rs

@@ -7,6 +7,7 @@ use crate::{
 };
 use std::{collections::BTreeMap, fs};
 
+use anyhow::Context;
 use serde::Deserialize;
 
 #[derive(Deserialize, Clone, Debug)]
@@ -47,7 +48,7 @@ pub struct Settings {
 }
 
 pub fn init_config() -> Result<Settings> {
-    let file = fs::read_to_string("./config.toml")?;
+    let file = fs::read_to_string("./config.toml").with_context(|| "read ./config.toml failed")?;
     let mut settings: Settings = toml::from_str(&file)?;
 
     // convert route map

src/consts.rs

@@ -1,6 +1,5 @@
 use std::{collections::BTreeMap, env, process::exit, sync::OnceLock};
 
-use anyhow::Context;
 use tracing::error;
 
 use crate::config::{init_config, Settings};
@@ -10,12 +9,8 @@ static SETTINGS: OnceLock<Settings> = OnceLock::new();
 pub fn get_settings() -> &'static Settings {
     SETTINGS.get_or_init(|| {
         init_config()
-            .with_context(|| "init config failed")
             .map_err(|err| {
-                error!("{err}");
-                if let Some(err) = err.source() {
-                    error!("cause by {:?}", err)
-                }
+                error!("get_or_init config failed: {err}");
                 exit(1);
             })
             .unwrap()

src/main.rs

@@ -1,9 +1,10 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 
 use tokio::task::JoinSet;
 use tracing::{debug, info};
 
 use crate::{
+    config::init_config,
     consts::{get_settings, ARCH, NAME, OS, VERSION},
     utils::init_logger,
 };
@@ -18,6 +19,7 @@ mod utils;
 #[tokio::main]
 async fn main() -> Result<()> {
     init_logger();
+    init_config().with_context(|| "init config failed")?;
 
     // global config
     let settings = get_settings();