Function nova_rt_eprint 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn nova_rt_eprint(s: *const NovaStr)

Write s to stderr with no trailing newline.

Mirrors nova_rt_print’s explicit lock-and-flush shape rather than nova_rt_println’s println!, but not its reason. Rust 1.95’s Stdout is a LineWriter unconditionally, so a partial line with no trailing newline can sit in that buffer until something flushes it – there, the explicit flush is load-bearing. Stderr carries no such buffer at all (Rust’s own source marks its raw handle “not buffered”), so a write reaches the OS on contact regardless of a trailing newline; the flush call below is a harmless no-op kept for symmetry with nova_rt_print, not a mechanism this stream needs.

Safety

s must point to a live NovaStr.