Function wasmtime_exn_new 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn wasmtime_exn_new(
    store: WasmtimeStoreContextMut<'_>,
    tag: &Tag,
    fields: *const wasmtime_val_t,
    nfields: usize,
    exn_ret: &mut *mut wasmtime_exn_t,
) -> Option<Box<wasmtime_error_t>>