errorfunction bug fix for nil

servicebuildermdl/servicebuildermdl.go

@@ -292,6 +292,9 @@ func (sb *ServiceBuilder) executeValidationFunction(dataKey string, fn func(inte
 
 // executeErrorFunction exceute when validation failed for any step
 func (sb *ServiceBuilder) executeErrorFunction(fn func() (map[string]interface{}, error)) (*interface{}, error) {
+	if fn == nil {
+		return nil, nil
+	}
 	_, err := fn()
 	if errormdl.CheckErr(err) != nil {
 		loggermdl.LogError(err)