message: feat(c-api) `wasm_$name_vec_delete` for boxed vec now takes an `Option<&mut T>`.
  This was already the case for regular vec. This patch applies the same
  pattern for boxed vec.
  See
diff: @@ -341,9 +341,8 @@ int main() {
  See the [`wasm_" $name "_vec_t`] type to get an example."]
  #[no_mangle]
  - pub unsafe extern "C" fn [<wasm_ $name _vec_delete>](ptr: *mut [<wasm_ $name _vec_t>]) {
  - let vec = &mut *ptr;
  -
  + pub unsafe extern "C" fn [<wasm_ $name _vec_delete>](ptr: Option<&mut [<wasm_ $name _vec_t>]>) {
  + if let Some(vec) = ptr {
  if !vec.data.is_null() {
  let data: Vec<*mut [<wasm_ $name _t>]> = Vec::from_raw_parts(vec.data, vec.size, vec.size);
  @@ -359,6 +358,7 @@ See the [`wasm_" $name "_vec_t`] type to get an example."]
  }
  }
  }
  + }
  wasm_declare_vec_inner!($name);
  };
  