fix: Include full error chain in procedure HTTP request errors

Walk the `source()` chain of `reqwest::Error` when converting to
`NodesError::HttpError`, so users see the underlying cause (DNS failure,
connection refused, timeout, TLS error, etc.) instead of just the
opaque top-level "error sending request for url" message.

Fixes #4608

Author: Shiven0504

crates/core/src/host/instance_env.rs

@@ -857,8 +857,18 @@ impl InstanceEnv {
             err
         }
 
-        fn http_error<E: ToString>(err: E) -> NodesError {
-            NodesError::HttpError(err.to_string())
+        fn http_error<E: std::error::Error>(err: E) -> NodesError {
+            // Include the full error chain, not just the top-level message.
+            // `reqwest::Error` wraps underlying causes (DNS failure, connection refused,
+            // timeout, TLS errors, etc.) which are essential for debugging.
+            use std::fmt::Write;
+            let mut message = err.to_string();
+            let mut source = err.source();
+            while let Some(cause) = source {
+                write!(message, ": {cause}").unwrap();
+                source = cause.source();
+            }
+            NodesError::HttpError(message)
         }
 
         // Then convert the request into an `http::Request`, a semi-standard "lingua franca" type in the Rust ecosystem,
@@ -888,7 +898,7 @@ impl InstanceEnv {
 
         // Check if we have a blocked IP address, since IP literals bypass DNS resolution.
         if is_blocked_ip_literal(reqwest.url()) {
-            return Err(http_error(BLOCKED_HTTP_ADDRESS_ERROR));
+            return Err(NodesError::HttpError(BLOCKED_HTTP_ADDRESS_ERROR.to_string()));
         }
 
         let redirect_policy = reqwest::redirect::Policy::custom(|attempt| {