rtmp: doing conn.close log message after we actually check that there is still a connection, otherwise we might have a nil logger and cause a panic

rtmp/conn.go

@@ -134,10 +134,10 @@ func Dial(url string, timeout uint, log Log) (*Conn, error) {
 // Close terminates the RTMP connection.
 // NB: Close is idempotent and the connection value is cleared completely.
 func (c *Conn) Close() error {
-	c.log(DebugLevel, pkg+"Conn.Close")
 	if !c.isConnected() {
 		return errNotConnected
 	}
+	c.log(DebugLevel, pkg+"Conn.Close")
 	if c.streamID > 0 {
 		if c.link.protocol&featureWrite != 0 {
 			sendFCUnpublish(c)