Add missed case for ip

config/type_bytes.go

@@ -38,6 +38,10 @@ func (c TypeBytes) MarshalText() ([]byte, error) {
 }
 
 func (c TypeBytes) String() string {
+	if c.value == 0 {
+		return ""
+	}
+
 	return strings.ToLower(c.value.String())
 }
 

config/type_ip_test.go

@@ -94,6 +94,7 @@ func (suite *TypeIPTestSuite) TestMarshalOk() {
 
 func (suite *TypeIPTestSuite) TestValue() {
 	testStruct := &typeIPTestStruct{}
+	suite.Empty(testStruct.Value.String())
 
 	suite.Nil(testStruct.Value.Value(nil))
 	suite.Equal("127.1.0.1", testStruct.Value.Value(net.ParseIP("127.1.0.1")).String())