Check the case with invalid token

src/tcp_relay_client/mod.rs

@@ -1,6 +1,7 @@
 extern crate core;
 
 use std::error::Error;
+use std::io::ErrorKind;
 use std::sync::Arc;
 
 use futures::future::join_all;
@@ -39,11 +40,13 @@ async fn get_server_config(conf: &ClientConfig) -> Result<RemoteConfig, Box<dyn
         .send()
         .await?;
     if req.status().as_u16() != 200 {
-        log::error!(
-            "Could not retrieve configuration! (got status {})",
-            req.status()
-        );
-        std::process::exit(2);
+        Err(std::io::Error::new(
+            ErrorKind::Other,
+            format!(
+                "Could not retrieve configuration! (got status {})",
+                req.status()
+            ),
+        ))?;
     }
 
     Ok(req.json::<RemoteConfig>().await?)
@@ -70,8 +73,11 @@ pub async fn run_app(mut args: ClientConfig) -> std::io::Result<()> {
     let remote_conf = match get_server_config(&args).await {
         Ok(c) => c,
         Err(e) => {
-            log::error!("Failed to fetch relay configuration from server! {}", e);
-            panic!();
+            Err(std::io::Error::new(
+                ErrorKind::Other,
+                format!("Failed to fetch relay configuration from server! {}", e),
+            ))?;
+            unreachable!();
         }
     };