Function set_safe_custom_backtrace_provider 

pub fn set_safe_custom_backtrace_provider<F>(provider: F) -> Result<(), Error>
where
    F: Fn() -> String + Send + Sync + 'static,

Overrides backtrace capture. The returned string lands verbatim in the stacktrace field of service.1 records and is treated as safe-to-log. Used for platforms like wasm with that backtrace::Backtrace doesn’t support.