Unable to get ast for wasm code

**Describe the bug**
When I try to get at form wat code, I'm getting errors

**To Reproduce**
Steps to reproduce the behavior:
1. My rust code looks like
```
#[no_mangle]
pub extern fn sum(x: i64, y: i64) -> i64 {
x + y
}
fn main() {}

```
2. Compile to wasm using `cargo build --release --target=wasm32-unknown-unknown`
3. Convert it into wat using `wasm2wat main.wasm -o main.wat`
4. Copy the wat code and put it on explorer.

**Expected behavior**
Should generate the ast

**Screenshots**

**Browser (please complete the following information):**
- OS: Ubuntu 18.04
- Browser: Brave
- Version: v84

**astexplorer settings:**
- Selected parser: wat-parser