must not define global members in ifdef'd block.

src/error.h

@@ -61,10 +61,10 @@ class Error : protected Pointers {
  private:
   std::string last_error_message;
   ErrorType last_error_type;
-
-  int numwarn, maxwarn, allwarn;
 #endif
+
  private:
+  int numwarn, maxwarn, allwarn;
   // internal versions that accept explicit fmtlib arguments
   [[ noreturn ]] void _all(const std::string &, int, fmt::string_view,
                            fmt::format_args args);