fix error handler on WrapNew/NopLogger cause nil pointer exception (#81)

Author: qneyrat

logger.go

@@ -115,12 +115,12 @@ func (l *Logger) WrapNew(middlewares ...MiddlewareInterface) LoggerInterface {
 	for _, middleware := range middlewares {
 		handler = middleware(handler)
 	}
-	return &Logger{handler: handler}
+	return &Logger{handler: handler, ErrorHandler: l.ErrorHandler}
 }
 
 // NewNopLogger will create a new no operating logger that log nowhere
 func NewNopLogger() *Logger {
-	return &Logger{handler: NopHandler}
+	return NewLogger(NopHandler)
 }
 
 // NewLogger will return a new logger

logger_test.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"log/syslog"
 	"os"
+	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -251,6 +252,41 @@ func TestNewLogger_WrapNew(t *testing.T) {
 	assert.Equal(t, 4, i)
 }
 
+func TestNewLogger_WrapNewErrorHandler(t *testing.T) {
+	mockHandlerCalled := false
+	mockHandler := func(entry logger.Entry) error {
+		mockHandlerCalled = true
+		assert.Equal(t, "l message", entry.Message)
+		assert.Equal(t, logger.DebugLevel, entry.Level)
+		assert.Equal(t, logger.Context{}, *entry.Context)
+
+		return errors.New("my handler error")
+	}
+	errorHandlerCalled := false
+	l := logger.NewLogger(mockHandler)
+	l.ErrorHandler = func(err error, entry logger.Entry) {
+		errorHandlerCalled = true
+		assert.EqualError(t, err, "my handler error")
+	}
+
+	l2 := l.WrapNew()
+
+	ptr1 := reflect.ValueOf(l.ErrorHandler).Pointer()
+	ptr2 := reflect.ValueOf(l2.(*logger.Logger).ErrorHandler).Pointer()
+	assert.Equal(t, ptr1, ptr2)
+
+	l.Debug("l message")
+	assert.True(t, mockHandlerCalled)
+	assert.True(t, errorHandlerCalled)
+
+	mockHandlerCalled = false
+	errorHandlerCalled = false
+
+	l2.Debug("l message")
+	assert.True(t, mockHandlerCalled)
+	assert.True(t, errorHandlerCalled)
+}
+
 // =====================================================================================================================
 // ================================================= EXAMPLES ==========================================================
 // =====================================================================================================================