getPreps returns error with high end ranking

[robcxyz]

Per title, when calling the getPreps rpc method with a high end ranking, it returns an error.

from pprint import pprint
import requests

url = "https://ctz.solidwallet.io/api/v3"

payload_working = {
    "jsonrpc": "2.0",
    "id": 1234,
    "method": "icx_call",
    "params": {
        "to": "cx0000000000000000000000000000000000000000",
        "dataType": "call",
        "data": {
            "method": "getPReps",
            "params": {
                "startRanking" : "0x1",
                "endRanking": "0xa"
            }
        }
    }
}

response = requests.post(url, json=payload_working).json()
pprint(response)

payload_broken = {
    "jsonrpc": "2.0",
    "id": 1234,
    "method": "icx_call",
    "params": {
        "to": "cx0000000000000000000000000000000000000000",
        "dataType": "call",
        "data": {
            "method": "getPReps",
            "params": {
                "startRanking" : "0x1",
                "endRanking": "0xaa" # Large 
            }
        }
    }
}

response = requests.post(url, json=payload_broken).json()
pprint(response)

Which returns:

{'error': {'code': -32001,
           'message': "'NoneType' object has no attribute 'to_dict'"},
 'id': 1234,
 'jsonrpc': '2.0'}

[goldworm-icon]

We confirmed that this error happens when endRanking is larger than the number of PRep candidates.
This bug will be fixed at the next version and we expect to release it until November.
Thanks for your feedback.

[cow-hs]

@robcxyz It is ICON Service issue.
it is my PR icon-project/icon-service#521.
Please check then close this issue.

[robcxyz]

Thanks!