Ethers.js: Error thrown from EtherscanProvider.call via FallbackProvider not catchable

[justinjmoses]

When the FallbackProvider.call invokes EtherscanProvider.call, the error thrown (https://github.com/ethers-io/ethers.js/blob/master/providers/etherscan-provider.js#L209) isn't catchable because the setTimeout has the error thrown on a different async stack: https://github.com/ethers-io/ethers.js/blob/master/providers/fallback-provider.js#L103.

If EtherscanProvider.call instead returns Promise.reject(...), it works as expected.

[ricmoo]

I’ll look into this today and check on v5 as well.

[ricmoo]

I'm trying to reproduce this. Do you have an example?

Were you able to reproduce it in node? Or in the browser?

[ricmoo]

(to be clear, looking at the code, I agree it should be a problem, but for some reason when I try to trigger the issue, it... doesn't crash in a disjoint way, like I expect it to. I want to make sure I can reproduce it so I know it is fixed. ;))

[ricmoo]

I was able to hack in a few lines into the list build to trigger this and confirmed the returning a Promise.reject fixed it. Just trying to sweep in a few more fixes and I'll publish.

Thanks for your patience. :)

[justinjmoses]

Ah sorry it was in node. Something like the below:

'use strict';

const {
  Contract,
  providers: { FallbackProvider, EtherscanProvider },
} = require('ethers');

const axios = require('axios');

(async function() {
  const network = 'homestead';
  const ETHERSCAN_API_KEY = 'YourApiKey';
  const provider = new FallbackProvider([
    new EtherscanProvider(network, ETHERSCAN_API_KEY),
  ]);

  try {
    const address = '0x545973f28950f50fc6c7F52AAb4Ad214A27C0564';
    const response = await axios.get(
      `https://api.etherscan.io/api?module=contract&action=getabi&address=${address}&apikey=${ETHERSCAN_API_KEY}`
    );

    const abi = JSON.parse(response.data.result);

    //  provider.
    const contract = new Contract(address, abi, provider);

    const maxEntries = await contract.maxEntriesInQueue({ blockTag: 97e5 });

    console.log('MaxEntries:', maxEntries);
  } catch (err) {
    console.error('Error:', err);
  }
})();

[justinjmoses]

But I can't seem to repro it right now with the blockTag error which is what was causing the issue - getting header not found now and it's catching as expected

[ricmoo]

Yeah, exactly what I was trying... It has to fail in a weird way and not on the first run (otherwise it fails in that async loop). It's ok, I just hacked in some things directly to force it to fail. :)

The fixes are in, but I'm looking through for other low-hanging fruit, since it takes about an hour for the tests to run and do all the admin tasks to cut a release. I'll update this ticket when it is published to npm.

[ricmoo]

Fixed and the CI is running. Once the tests have passed, I'll publish to npm.

[ricmoo]

This has been published to 4.0.46. Try it out and let me know if you have any problems. :)

[ricmoo]

Closing this now, but if you are still having problems, please re-open the issue.

Thanks! :)

[justinjmoses]

Haven't had a chance, but will keep an eye on it. Thanks @ricmoo