parseLog - Deferred error during ABI decoding triggered accessing property "to"

[TRCSamurai]

Describe the bug
It's a decoding/validation error when parsing a Transfer log using Interface.parseLog and then trying to access args.to of the decoded log.

Transaction: https://rinkeby.etherscan.io/tx/0xcbb6f53e05b3bfde1fde259f9b44d48fde73f4f633604cbe6bd4375dddbefa0f

Reproduction steps

===================
Code
===================
import {utils} from "ethers"

const rawLog = 
{
    blockNumber: 10172601,
    blockHash: '0xe386d2275b6db3b1e02d5fae3f663312ecbf4f5f58fdf20c47da5fb6769dc578',
    transactionIndex: 5,
    removed: false,
    address: '0x1607a02df130c472159fAEb2BC706175B84055Fa',
    data: '0x0000000000000000000000000000000000000000000000000000000000000000',
    topics: [
      '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
      '0x00000000000000000000000073c9cc436c1249394d1ea28bf1d9f2217da006f4',
      '0x4567000000000000000000000000000000000000000000000000000000000000'
    ],
    transactionHash: '0xcbb6f53e05b3bfde1fde259f9b44d48fde73f4f633604cbe6bd4375dddbefa0f',
    logIndex: 11
  }

const ABI = [ "event Transfer(address indexed from, address indexed to, uint value)" ]

const output = (new utils.Interface(ABI)).parseLog(rawLog)

console.log(output.args.to) // error

===================
output.args Output
===================  
 [
    '0x73c9cC436C1249394D1eA28BF1d9F2217dA006f4',
    [Getter],
    BigNumber { _hex: '0x00', _isBigNumber: true },
    from: '0x73c9cC436C1249394D1eA28BF1d9F2217dA006f4',
    to: [Getter],
    value: BigNumber { _hex: '0x00', _isBigNumber: true }
  ]
  
===================
Error
===================  
Error: deferred error during ABI decoding triggered accessing property "to" {
    reason: 'value out of range',
    code: 'INVALID_ARGUMENT',
    argument: 'value',
    value: 20,
    baseType: 'address',
    type: 'address'
  }

I'm guessing it's a validation error, since the error is an array and not a string.
                 

Environment:

Ubuntu v20.04
Node JS  v16.6.2
Ethers JS v5.5.2

[ricmoo]

Yes, this error indicates that the data is invalid, but ethers tries to keep things together as long as possible, so that if you, for example, didn't require the to, it won't fail.

If you look at the above topics,

// id("Transfer(address, address,uint256)")
topic0 = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"

// The indexed `from`
topic1 = "0x00000000000000000000000073c9cc436c1249394d1ea28bf1d9f2217da006f4"

// The indexed `to`
topic2 = "0x4567000000000000000000000000000000000000000000000000000000000000"

// The `value`
data = "0x0000000000000000000000000000000000000000000000000000000000000000"

As you can see the value for topic2 is invalid. It has 2 bytes (4 nibbles) non-zero at the top so it is out of range.

The contract is not verified, but decompiling it, it simply hard-codes the event to emit (using log3), but if you modify the ABI a bit, you can see that it just has its indexed properties rearranged. If you change the signature to Transfer(address indexed from, address to, uint256 indexed value), it will likely parse fine (notice the to is not indexed in the updated signature). I think its likely just a bug or someone experimenting, but it could also be the event signature is not ERC-721 or ERC-20.

Does that make sense?

[TRCSamurai]

Yes is does, thank you for the explanation!