Remix plugin: Disable verification when Etherscan is selected and no constructor arguments provided

[manuelwedler]

Etherscan is the only verifier that requires constructor arguments for verification. At the moment it is possible to hit the "verify" button even if no constructor arguments are provided. If Etherscan is selected, we can provide better feedback to the user. We should disable the button and show an error message in this case.

[manuelwedler]

Opened a PR for this: ethereum/remix-project#5808

[kuzdogan]

Looking at the API again, it says it's optional but is it actually required of the contract has constructor arguments? Not really clear to me

https://docs.etherscan.io/api-endpoints/contracts

[manuelwedler]

I tried it. It is definitely required if your contract has constructor arguments.