[p2][LCD]Encounter incorrect return while trying to set an empty address for "/distribution/{address}/rewards"

[shilei-wang]

Describe the bug
It seems the system fail to handle the condition in which the address input is empty.

Since the iriscli and swagger will both intercept empty address input, this bug has never been discovered.

To Reproduce
http://localhost:1317/distribution/""/rewards

The system fails to analysis (“”)，and then returns the confused output:

---

{
  "total": [
    {
      "denom": "iris-atto",
      "amount": "1114165332000000000"
    }
  ],
  "delegations": [
    {
      "validator": "fva19q9utf40ecgsumacxtne7rhs5kl32v6nzk88ke",
      "reward": [
        {
          "denom": "iris-atto",
          "amount": "531869301000000000"
        }
      ]
    },
    {
      "validator": "fva1lwfd8p7nywdxm4xyn8dafe8uhu7w39ap0v4csz",
      "reward": [
        {
          "denom": "iris-atto",
          "amount": "582296031000000000"
        }
      ]
    }
  ],
  "commission": null
}

[shilei-wang]

confirmed