Small improvements

internal/nbconn/nbconn.go

@@ -97,7 +97,7 @@ type NetConn struct {
 	writeDeadlineLock sync.Mutex
 	writeDeadline     time.Time
 
-	// Indicates that underlying socket connection mode set to be non-blocking
+	// Indicates that underlying socket connection mode explicitly set to be non-blocking
 	isNonBlocking bool
 }
 

internal/nbconn/nbconn_real_non_block_windows.go

@@ -164,9 +164,11 @@ func (c *NetConn) SetBlockingMode(blocking bool) error {
 
 	var err error
 
-	c.rawConn.Control(func(fd uintptr) {
+	if ctrlErr := c.rawConn.Control(func(fd uintptr) {
 		err = setSockMode(fd, mode)
-	})
+	}); ctrlErr != nil {
+		return ctrlErr
+	}
 
 	if err == nil {
 		c.isNonBlocking = !blocking