Surface service forwarder failures

src/bin/dosh-client.rs

@@ -2380,8 +2380,21 @@ struct FileForwarder {
 
 impl Drop for FileForwarder {
     fn drop(&mut self) {
-        let _ = self.child.kill();
-        let _ = self.child.wait();
+        let exited = self.child.try_wait().ok().flatten();
+        if exited.is_none() {
+            let _ = self.child.kill();
+            let _ = self.child.wait();
+            return;
+        }
+        if exited.is_some_and(|status| !status.success()) {
+            let mut stderr = String::new();
+            if let Some(mut pipe) = self.child.stderr.take() {
+                let _ = pipe.read_to_string(&mut stderr);
+            }
+            if !stderr.trim().is_empty() {
+                eprintln!("Dosh service forwarder failed:\n{}", stderr.trim_end());
+            }
+        }
     }
 }