Add undefined return type in onMutate

[eomttt]

useMutation has void return type but in code has not

In my code

  const onMutate = () => {
    const previous = queryClient.getQueryData<CartProductsDataType>(queryKey);
    return previous;
  };
  const onError = (error: any, variable: AddOptionItem, context: CartProductsDataType | undefined) => {
    queryClient.setQueryData(queryKey, context);
  };

  return useMutation(QueryKey.CARTS, mutateFn, {
    onMutate,
    onError,
  });

onMutate return CartProductsDataType or undefind because of getQueryData but in useMutation error!!!
because useMutation onMutate function type only return Promise<Context> or Context not has undefined
so i try to add undefined type in onMutate return type

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