Okapi obfuscates compiler errors

Thank you for this project! I've been struggling with documenting an API I build, and keeping that documentation up to date. I'm trying to add okapi to my project to have the documentation be created automatically. Unfortunately, I'm running into some issues:

As it stands, Rocket is able to provide neat Rust error messages. Consider the following example:
```
#![feature(decl_macro, proc_macro_hygiene)]

use rocket::{get, routes};
use rocket_contrib::json::Json;

#[derive(serde::Serialize)]
struct Response {
reply: String,
}

#[get("/")]
fn my_controller() -> Json {
Json(Response {
reply: 0,
})
}

fn main() {
rocket::ignite()
.mount("/", routes![my_controller])
.launch();
}
```
This fails with a compile error:
```
[me@mycomputer tmp]$ cargo check
Checking tmp v0.1.0 (/home/me/code/rust/tmp)
error[E0308]: mismatched types
--> src/main.rs:17:16
|
17 | reply: 0,
| ^
| |
| expected struct `std::string::String`, found integer
| help: try using a conversion method: `0.to_string()`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
error: could not compile `tmp`.
```
However, when the code is changed to use Okapi:
```
#![feature(decl_macro, proc_macro_hygiene)]

use rocket::get;
use rocket_contrib::json::Json;
use rocket_okapi::{openapi, routes_with_openapi};
use schemars::JsonSchema;

#[derive(serde::Serialize, JsonSchema)]
struct Response {
reply: String,
}

#[openapi]
#[get("/")]
fn my_controller() -> Json {
Json(Response {
reply: 0,
})
}

fn main() {
rocket::ignite()
.mount("/", routes_with_openapi![my_controller])
.launch();
}
```
The error message changes:
```
[me@mycomputer tmp]$ cargo check
Checking tmp v0.1.0 (/home/me/code/rust/tmp)
error[E0308]: mismatched types

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
error: could not compile `tmp`.
```
The useful information about what caused the compilation error is gone, making it really hard to debug. Is there any way to get it back?