BUG: make Value non-abstract class

include/caosdb/value.h

@@ -247,9 +247,8 @@ public:
     static const std::vector<ScalarValue> empty_collection;
     return empty_collection;
   }
-  inline auto ToString() const noexcept -> const std::string {
-    CAOSDB_DEBUG_MESSAGE_STRING(*wrapped, out)
-    return out;
+  [[nodiscard]] inline auto ToString() const noexcept -> const std::string {
+    return ProtoMessageWrapper::ToString();
   }
 
   friend class Value;
@@ -416,6 +415,10 @@ public:
     return *this;
   }
 
+  [[nodiscard]] inline auto ToString() const noexcept -> const std::string {
+    return ProtoMessageWrapper::ToString();
+  }
+
   friend class Entity;
   friend class Property;