I got this piece of code that won’t compile.

[dependencies] tokio = {version = "1.37.0", features = ["full"]}

use std::error::Error;

async fn external_function() -> Result<i32, Box<dyn Error>>{
  println!("This is an external function!");
  Ok(1)
}

async fn my_function(something: i32) {
  println!("This is my function {something}");
}

#[tokio::main]
async fn main() {
  println!("Hello, world!");
  let runtime = tokio::runtime::Runtime::new().unwrap();
    runtime.spawn(async move {
      let v = external_function().await;
      if let Ok(x) = v {
          my_function(x).await;
      }
    });
}

The issue is that I got an async function from a crate that returns a Result<T, Box<dyn Error>>
I want to process these results, and if it’s Ok() call my function with the resulting value.

But I got this compiler error: error: future cannot be sent between threads safely

What would be the best practice to implement this without errors, given that I cannot modify the external_function()?

One solution would be to make my_function() non async, but what if I’d want that to be async as well?