security: Throw exception when loading on orphaned ValidationPolicyConfig

ValidationPolicyConfig must be assigned to a Validator instance prior to
loading and it is an API violation to load configuration otherwise.

Change-Id: Ib372cd3b6ab7c7ce1e37039f25b97e1d2f1511f9
Refs: #4758
diff --git a/src/security/v2/validation-policy-config.cpp b/src/security/v2/validation-policy-config.cpp
index ff3f7bf..763bef1 100644
--- a/src/security/v2/validation-policy-config.cpp
+++ b/src/security/v2/validation-policy-config.cpp
@@ -75,6 +75,9 @@
 void
 ValidationPolicyConfig::load(const ConfigSection& configSection, const std::string& filename)
 {
+  if (m_validator == nullptr) {
+    BOOST_THROW_EXCEPTION(Error("Validator instance not assigned on the policy"));
+  }
   if (m_isConfigured) {
     m_shouldBypass = false;
     m_dataRules.clear();