refactor: update examples to return LightstreamerError

- Add From<VarError> impl to LightstreamerError for env::var support
- Update all 7 example binaries to return LightstreamerError instead of Box<dyn Error>

Author: joaquinbejar

examples/simple/src/bin/channel_example.rs

@@ -15,7 +15,7 @@ const MAX_CONNECTION_ATTEMPTS: u64 = 1;
 /// item updates through a tokio channel, enabling asynchronous processing
 /// in a separate task.
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     setup_logger();
 
     info!("🚀 Starting Channel-based Subscription Example");

examples/simple/src/bin/connection_manager_example.rs

@@ -72,7 +72,7 @@ impl SubscriptionListener for ConnectionAwareListener {
 }
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     setup_logger();
 
     info!("🚀 Starting ConnectionManager Example");
@@ -223,7 +223,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 fn create_stock_subscription(
     name: &str,
     items: Vec<&str>,
-) -> Result<Subscription, Box<dyn std::error::Error>>
+) -> Result<Subscription, lightstreamer_rs::utils::LightstreamerError>
 where
     Subscription: Sized,
 {

examples/simple/src/bin/easy.rs

@@ -15,7 +15,7 @@ use lightstreamer_rs::utils::setup_logger;
 use tracing::info;
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     setup_logger();
 
     info!("🚀 Starting Easy Lightstreamer Example");

examples/simple/src/bin/ig.rs

@@ -25,7 +25,7 @@ pub struct Config {
 }
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     setup_logger();
     //
     // Create a new subscription instance.

examples/simple/src/bin/ig_advanced.rs

@@ -44,7 +44,7 @@ impl SubscriptionListener for AdvancedFinancialListener {
 }
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     setup_logger();
     info!("🚀 Starting IG Markets Advanced Lightstreamer Client with ConnectionManager");
 

examples/simple/src/bin/minimal.rs

@@ -10,7 +10,7 @@ use lightstreamer_rs::client::{ClientConfig, SimpleClient, SubscriptionParams};
 use lightstreamer_rs::subscription::SubscriptionMode;
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     // 1. Configure
     let config =
         ClientConfig::new("http://push.lightstreamer.com/lightstreamer").adapter_set("DEMO");

examples/simple/src/bin/simple.rs

@@ -38,7 +38,7 @@ impl SubscriptionListener for MySubscriptionListener {
 }
 
 #[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
+async fn main() -> Result<(), lightstreamer_rs::utils::LightstreamerError> {
     setup_logger();
     //
     // Create a new subscription instance.

src/utils/error.rs

@@ -199,6 +199,12 @@ impl From<crate::connection::ReconnectionError> for LightstreamerError {
     }
 }
 
+impl From<std::env::VarError> for LightstreamerError {
+    fn from(e: std::env::VarError) -> Self {
+        LightstreamerError::Configuration(e.to_string())
+    }
+}
+
 /// Legacy exception type for backward compatibility.
 /// Prefer using `LightstreamerError::InvalidArgument` directly.
 #[deprecated(