ENH: Add status code for wrong void pointer assignment

include/caosdb/status_code.h

@@ -52,6 +52,7 @@ enum StatusCode {
   TRANSACTION_TYPE_ERROR = 26,
   UNSUPPORTED_FEATURE = 27,
   ORIGINAL_ENTITY_MISSING_ID = 28,
+  EXTERN_C_ASSIGNMENT_ERROR = 29,
 };
 
 auto get_status_description(int code) -> const std::string &;

src/caosdb/transaction.cpp

@@ -80,7 +80,10 @@ auto get_status_description(int code) -> const std::string & {
      "an id. This is the case when you did not retrieve it before applying any "
      "changes and instantiated the Entity class explicitely."},
     {StatusCode::UNSUPPORTED_FEATURE,
-     "This feature is not available in the this client implementation."}};
+     "This feature is not available in the this client implementation."},
+    {StatusCode::EXTERN_C_ASSIGNMENT_ERROR,
+     "You tried to assign a new object to the wrapped void pointer. You have "
+     "to delete the old pointee first."}};
   try {
     return descriptions.at(code);
   } catch (const std::out_of_range &exc) {