Fix wast field is missing

[wtdcode]

Motivation

The wast field maybe missing in solc compiler output.

JSON input:

{
    "language": "Solidity",
    "sources": {
        "src.sol": {
            "content": "contract T{}"
        }
    },
    "settings": {
        "optimizer": {
            "enabled": false,
            "runs": 200
        },
        "outputSelection": {
            "*": {
                "": [
                    "*"
                ],
                "*": [
                    "*"
                ]
            }
        },
        "evmVersion": "london",
        "libraries": {}
    }
}

Output:

/tmp $ solc --standard-json < compile.json | jq . | grep -C1 wasm
        },
        "ewasm": {
          "wasm": ""
        },
/tmp $

This is causing failure to deserialize compilers json outputs while the compilation is successful.

Solution

As proposed.

PR Checklist

• Added Tests

No need for tests.

• Added Documentation

No need for further docs.

• Breaking changes

This shouldn't introduce any breaking changes.