fix: avoid potential "no user-provided default constructor" error

Author: kwvg

src/evo/deterministicmns.h

@@ -394,13 +394,14 @@ class CDeterministicMNList
     template <typename T>
     [[nodiscard]] uint256 GetUniquePropertyHash(const T& v) const
     {
-        static_assert(!std::is_same<T, CBLSPublicKey>(), "GetUniquePropertyHash cannot be templated against CBLSPublicKey");
+        static_assert(!std::is_same_v<std::decay_t<T>, CBLSPublicKey>,
+                      "GetUniquePropertyHash cannot be templated against CBLSPublicKey");
         return ::SerializeHash(v);
     }
     template <typename T>
     [[nodiscard]] bool AddUniqueProperty(const CDeterministicMN& dmn, const T& v)
     {
-        static const T nullValue;
+        static const T nullValue{};
         if (v == nullValue) {
             return false;
         }
@@ -420,7 +421,7 @@ class CDeterministicMNList
     template <typename T>
     [[nodiscard]] bool DeleteUniqueProperty(const CDeterministicMN& dmn, const T& oldValue)
     {
-        static const T nullValue;
+        static const T nullValue{};
         if (oldValue == nullValue) {
             return false;
         }
@@ -443,7 +444,7 @@ class CDeterministicMNList
         if (oldValue == newValue) {
             return true;
         }
-        static const T nullValue;
+        static const T nullValue{};
 
         if (oldValue != nullValue && !DeleteUniqueProperty(dmn, oldValue)) {
             return false;