message: Testing whether the table to be rename renamed exists.
diff: @@ -144,6 +144,9 @@ void SchemaCatalogEntry::AlterTable(ClientContext &context, AlterTableInfo *info
  case AlterTableType::RENAME_TABLE: {
  auto &transaction = Transaction::GetTransaction(context);
  auto entry = tables.GetEntry(transaction, info->table);
  + if(entry == nullptr) {
  + throw CatalogException("Table \"%s\" doesn't exist!", info->table.c_str());
  + }
  assert(entry->type == CatalogType::TABLE);
  auto copied_entry = entry->Copy(context);
  