rust-analyzer crashes when trying to use tokio::spawn async

**type: Bug**

**rust-analyzer version**: nightly cb78c40, stable branch has same error.

***Step-By-Step guide*** 
https://asciinema.org/a/gFUmLyfowCRD96ZrFEwsC3GYz

**Reproduce code** 
```rust
#[tokio::main]
pub async fn main() {
  println!("123");
  tokio::spawn(async {
//here ls server crashes 
});
}
```
