Fix CodeQL alert

Author: marlenecota

Diff for: include/fmt/base.h

@@ -1902,7 +1902,9 @@ template <typename Context> class basic_format_args {
     if (id >= detail::max_packed_args) return arg;
     arg.type_ = type(id);
     if (arg.type_ == detail::type::none_type) return arg;
-    arg.value_ = values_[id];
+    if (id >= 0) {
+      arg.value_ = values_[id];
+    }
     return arg;
   }