A bug found in simulateBlocks

[UnsignedInt8]

Hey, viem developer team.

When I make a simulateCalls request (which internally calls simulateBlocks), the response may look like this:

{
  "gasUsed": "0x62c8",
  "logs": [
    {
      "address": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
      "blockHash": null,
      "blockNumber": "0x15054d9",
      "blockTimestamp": "0x67d38512",
      "data": "0x0000000000000000000000000000000000000000000000000000000000000000",
      "logIndex": "0x0",
      "removed": false,
      "topics": [
        "0xe1fffcc4923d04b559f4d29a8bfc6cda04eb5b0d3c460751c2402c5c5cc9109c",
        "0x0000000000000000000000000000000000000000000000000000000000000000"
      ],
      "transactionHash": "0xab7207925279ea369265081ea4892388e0cf19c3aa3314c0285241faeef4ea6f",
      "transactionIndex": "0x0"
    }
  ],
  "returnData": "0x",
  "status": "0x1"
}

The corresponding ABI is:

[{"name":"tokenURI","type":"function","stateMutability":"nonpayable","inputs":[{"type":"uint256"}],"outputs":[{"type":"string"}]]"

However, this response cannot be decoded using decodeFunctionResult (in simulateBlocks) because the returnData is "0x".

To handle this issue, I added a condition to check if data !== '0x', and everything works fine now:

  const result =
          abi && status === 'success' && data != '0x'
            ? decodeFunctionResult({
                abi,
                data,
                functionName,
              })
            : null

viem/src/actions/public/simulateBlocks.ts

Line 246 in 06518ed

abi && status === 'success'

[UnsignedInt8]

A PR has been submitted #3445

[UnsignedInt8]

Merged! 🎉