Add an error log to debug errors on the ci test

Relates to #270

association.go

@@ -507,6 +507,8 @@ func (a *Association) closeAllTimers() {
 
 func (a *Association) readLoop() {
 	var closeErr error
+
+	a.log.Debugf("[%s] readLoop entered", a.name)
 	defer func() {
 		// also stop writeLoop, otherwise writeLoop can be leaked
 		// if connection is lost when there is no writing packet.
@@ -526,9 +528,14 @@ func (a *Association) readLoop() {
 		a.log.Debugf("[%s] stats nT3Timeouts : %d", a.name, a.stats.getNumT3Timeouts())
 		a.log.Debugf("[%s] stats nAckTimeouts: %d", a.name, a.stats.getNumAckTimeouts())
 		a.log.Debugf("[%s] stats nFastRetrans: %d", a.name, a.stats.getNumFastRetrans())
+
+		if errors.Is(closeErr, net.ErrClosed) || errors.Is(closeErr, io.EOF) {
+			a.log.Debugf("[%s] readLoop exited %s", a.name, closeErr)
+		} else {
+			a.log.Errorf("[%s] readLoop exited %s", a.name, closeErr)
+		}
 	}()
 
-	a.log.Debugf("[%s] readLoop entered", a.name)
 	buffer := make([]byte, receiveMTU)
 
 	for {
@@ -549,8 +556,6 @@ func (a *Association) readLoop() {
 			break
 		}
 	}
-
-	a.log.Debugf("[%s] readLoop exited %s", a.name, closeErr)
 }
 
 func (a *Association) writeLoop() {