recover for conn.Close fix #1333

grace/conn.go

@@ -1,13 +1,28 @@
 package grace
 
-import "net"
+import (
+	"errors"
+	"net"
+)
 
 type graceConn struct {
 	net.Conn
 	server *Server
 }
 
-func (c graceConn) Close() error {
+func (c graceConn) Close() (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			switch x := r.(type) {
+			case string:
+				err = errors.New(x)
+			case error:
+				err = x
+			default:
+				err = errors.New("Unknown panic")
+			}
+		}
+	}()
 	c.server.wg.Done()
 	return c.Conn.Close()
 }