fix possible nil panic in tests (#5720)

* fix maybe nil panic

* reset code

tests/callbacks_test.go

@@ -113,6 +113,9 @@ func TestCallbacks(t *testing.T) {
 
 	for idx, data := range datas {
 		db, err := gorm.Open(nil, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
 		callbacks := db.Callback()
 
 		for _, c := range data.callbacks {

tests/transaction_test.go

@@ -102,7 +102,7 @@ func TestTransactionWithBlock(t *testing.T) {
 		return errors.New("the error message")
 	})
 
-	if err.Error() != "the error message" {
+	if err != nil && err.Error() != "the error message" {
 		t.Fatalf("Transaction return error will equal the block returns error")
 	}