Initialize dst with zeros in the Node backend

src/js.rs

@@ -33,6 +33,9 @@ pub(crate) unsafe fn getrandom_inner(mut dst: *mut u8, mut len: usize) -> Result
 
         match source {
             RngSource::Node(n) => {
+                // We have to create a slice to pass it to the Node function.
+                // Since `dst` may be uninitialized, we have to initialize it first.
+                core::ptr::write_bytes(dst, 0, len);
                 let dst = core::slice::from_raw_parts_mut(dst, len);
                 if n.random_fill_sync(dst).is_err() {
                     return Err(Error::NODE_RANDOM_FILL_SYNC);