Hanging promise canceled using Rust in Cloudflare workers [wasm futures]

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1

I'm trying to set Cloudflare's workers to track the circulation of some ERC20 tokens as an exercise to learn web3 and wasm. Thought it could be simple enough, but about 90% of the time so far has been trying to solve this elusive error

A hanging Promise was canceled. This happens when the worker runtime is waiting for a Promise from JavaScript to resolve but has detected that the Promise cannot possibly ever resolve because all code and events related to the Promise's request context have already finished.

I look for additional information online, but it seems my error is from a different type(?).

Here's a simple snippet of code to reproduce.

mod erc20_abi;

use erc20_abi::ERC20_ABI;

use cfg_if::cfg_if;

use ethers::{
    contract::Contract,
    core::{abi::Abi, types::Address},
    prelude::{AbiError, U256},
    providers::{Http, Provider},
};
use num_format::{Locale, ToFormattedString};
use std::convert::TryFrom;
use wasm_bindgen::prelude::*;
cfg_if! {
    // When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
    // allocator.
    if #[cfg(feature = "wee_alloc")] {
        extern crate wee_alloc;
        #[global_allocator]
        static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
    }
}

#[wasm_bindgen]
pub async fn handle() -> String {

    let web3_ethereum = Provider::<Http>::try_from(WEB3_URL_ETHEREUM).unwrap();

    let abi: Abi = serde_json::from_str(ERC20_ABI).unwrap();

    let token_contract_ethereum = Contract::new(parse_address(ADDRESS_ETH), 
    abi, web3_ethereum);

    let convert_wei_to_decimal = |bignumber: U256| -> String {
        (bignumber.as_u128() / u128::pow(10, 18)).to_formatted_string(&Locale::en)
    };

    // I believe this is the problem, since just returning a String works fine.
    let total_supply_ethereum = token_contract_ethereum
        .method::<_, U256>("totalSupply", ())
        .unwrap()
        .call()
        .await
        .unwrap();


    convert_wei_to_decimal(total_supply_ethereum)
}

fn parse_address(address: &str) -> Address {
    address.parse::<Address>().unwrap()
}

This is the worker/workers.js file

addEventListener('fetch', (event) => {
    event.respondWith(handleRequest(event.request))
})

const { handle } = wasm_bindgen;
const instance = wasm_bindgen(wasm);
/**
 * Fetch and log a request
 * @param {Request} request
 */
async function handleRequest(request) {
    await instance;
    const output = await handle();
    let res = new Response(output, { status: 200 });
    res.headers.set('Content-type', 'text/html');
    return res;
}

Cargo.toml

[package]
name = "circulating-supply"
version = "0.1.0"
license = "GPL-3.0-or-later"
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[lib]
crate-type = ["cdylib", "rlib"]

[profile.release]
opt-level = 's'  # Optimize for size.
lto = true
panic = "abort"
codegen-units = 1

[dependencies]
ethers = { git = "https://github.com/gakonst/ethers-rs" }
serde_json = "1.0.68"
num-format = "0.4.0"
cfg-if = "1.0.0"
wee_alloc = { version = "0.4.5", optional = true }
wasm-bindgen = "0.2.78"
wasm-bindgen-futures = "0.4.28"
js-sys = "0.3.55"

wrangler dev will compile it fine, but going to http://127.0.0.1:8787 will result in Error 1101

2

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