If that's okay with you, I think this will be better handled without STL altogether, which is what #499 is meant to do. I'll finish & merge that PR once I have some free time again, unfortunately the top-priority tasks I have for this month don't include it.
Just FYI, this is fixed with d89b882ccf4d4af6c4a1f9e9c7ef63ddffaee85b. The std::string callback is still present for backwards compatibility, but to avoid a temporary allocation use a StringView instead.
If that's okay with you, I think this will be better handled without STL altogether, which is what #499 is meant to do. I'll finish & merge that PR once I have some free time again, unfortunately the top-priority tasks I have for this month don't include it.