fix(awc): prevent panics in pool drop for h1 connections (#3448)

Author: robjtede

awc/CHANGES.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Prevent panics on connection pool drop when Tokio runtime is shutdown early.
 - Minimum supported Rust version (MSRV) is now 1.75.
 
 ## 3.5.1

awc/src/client/pool.rs

@@ -76,7 +76,9 @@ where
     fn close(&self, conn: ConnectionInnerType<Io>) {
         if let Some(timeout) = self.config.disconnect_timeout {
             if let ConnectionInnerType::H1(io) = conn {
-                actix_rt::spawn(CloseConnection::new(io, timeout));
+                if tokio::runtime::Handle::try_current().is_ok() {
+                    actix_rt::spawn(CloseConnection::new(io, timeout));
+                }
             }
         }
     }