Handle missing bytecode during verification more gracefully

[antazoey]

Overview

I have never encountered this problem but noticed it while looking at the Hardhat source code:

  if (etherscanResponse.isBytecodeMissingInNetworkError()) {
    throw new NomicLabsHardhatPluginError(
      pluginName,
      `Failed to send contract verification request.
Endpoint URL: ${url}
Reason: The Etherscan API responded that the address ${req.contractaddress} does not have bytecode.
This can happen if the contract was recently deployed and this fact hasn't propagated to the backend yet.
Try waiting for a minute before verifying your contract. If you are invoking this from a script,
try to wait for five confirmations of your contract deployment transaction before running the verification subtask.`
    );
  }

We should probably offering a similar error handling here.

Specification

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Remember, your feature is much more likely to be included if it does not involve any breaking changes.

Dependencies

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