Referendum Proposals: assertion failure with message: cannot vote on an expired proposal.

[gluneau]

For the Referendum Proposals, perhaps you should have a filter for expired proposals.

Details:
{
  "code": 500,
  "message": "Internal Service Error",
  "error": {
    "code": 3050003,
    "name": "eosio_assert_message_exception",
    "what": "eosio_assert_message assertion failure",
    "details": [
      {
        "message": "assertion failure with message: cannot vote on an expired proposal.",
        "file": "wasm_interface.cpp",
        "line_number": 917,
        "method": "eosio_assert"
      },
      {
        "message": "pending console output: ",
        "file": "apply_context.cpp",
        "line_number": 72,
        "method": "exec_one"
      }
    ]
  }
}