Curl example doesn't compile : method not found in Option<&NgxStr>

[mtb0x1]

Describe the bug
I can't compile curl example, error message :

error[E0599]: no method named `as_bytes` found for enum `Option` in the current scope
   --> examples/curl.rs:114:37
    |
114 |             if request.user_agent().as_bytes().starts_with(b"curl") {
    |                                     ^^^^^^^^ method not found in `Option<&NgxStr>`
    |
note: the method `as_bytes` exists on the type `&NgxStr`
   --> /home/user/apps/rust/ngx-rust/src/core/string.rs:55:5
    |
55  |     pub fn as_bytes(&self) -> &[u8] {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: consider using `Option::expect` to unwrap the `&NgxStr` value, panicking if the value is an `Option::None`
    |
114 |             if request.user_agent().expect("REASON").as_bytes().starts_with(b"curl") {
    |                                    +++++++++++++++++

For more information about this error, try `rustc --explain E0599`.
error: could not compile `examples` (example "curl") due to previous error

To Reproduce
Steps to reproduce the behavior:

1. Run cargo build --release --package=examples --example=curl
2. See error

Expected behavior
Curl example compiles without errors

Your environment

• Repo version : Last version up to date (9ce7895)
• Version of Rust : stable, rustc 1.73.0 (cc66ad468 2023-10-03)
• OS and distribution : Debian bookworm

Additional context
N/A