check error before GotConn for trace

Signed-off-by: Ye Sijun <[email protected]>

Author: junnplus

client.go

@@ -319,14 +319,14 @@ func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader h
 	}
 
 	netConn, err := netDial("tcp", hostPort)
+	if err != nil {
+		return nil, nil, err
+	}
 	if trace != nil && trace.GotConn != nil {
 		trace.GotConn(httptrace.GotConnInfo{
 			Conn: netConn,
 		})
 	}
-	if err != nil {
-		return nil, nil, err
-	}
 
 	defer func() {
 		if netConn != nil {