“ledger_entry” with request improperly specified a Currency Code field do not return "malformedCurrency"

Expected response: `malformedCurrency`
Actual response: `invalidParams`


Sample request:
`{
  "method": "ledger_entry",
  "params": [{
    "ripple_state": {
      "accounts": [
        "rEgAvY1qyEfZxwSaDg5UdLtNQzyvSPEXtV",
        "rhyxmFfxujVTfxBjug37kouzms6YzWpAUy"
      ],
      "currency": "aa"
    },
    "ledger_index": "validated"
  }]
}`