json：无法将字符串解组为map [string] interface {}类型的Go值

I have been working on converting some crypto pool software over to work with an incompatible coin. I believe I have it all about done. But this error keeps popping up and I just can't seem to figure out what the problem is. Here is my code:

type GetBalanceReply struct {
    Unspent string `json:"unspent"`
}

type SendTransactionReply struct {
    Hash string `json:"hash"`
}

type RPCClient struct {
    sync.RWMutex
    Url         string
    Name        string
    Account     string
    Password    string
    sick        bool
    sickRate    int
    successRate int
    client      *http.Client
}


type GetBlockReply struct {
    Difficulty       string `json:"bits"`
    Hash             string `json:"hash"`
    MerkleTreeHash   string `json:"merkle_tree_hash"`
    Nonce            string `json:"nonce"`
    PrevHash         string `json:"previous_block_hash"`
    TimeStamp        string `json:"time_stamp"`
    Version          string `json:"version"`
    Mixhash          string `json:"mixhash"`
    Number           string `json:"number"`
    TransactionCount string `json:"transaction_count"`
}

type GetBlockReplyPart struct {
    Number     string `json:"number"`
    Difficulty string `json:"bits"`
}

type TxReceipt struct {
    TxHash string `json:"hash"`
}


type Tx struct {
    Gas      string `json:"gas"`
    GasPrice string `json:"gasPrice"`
    Hash     string `json:"hash"`
}

type JSONRpcResp struct {
    Id          *json.RawMessage       `json:"id"`
    Result      *json.RawMessage       `json:"result"`
    Balance     *json.RawMessage       `json:"balance"`
    Transaction *json.RawMessage       `json:"transaction"`
    Error  map[string]interface{} `json:"error"`
}


func (r *RPCClient) GetPendingBlock() (*GetBlockReplyPart, error) {
    rpcResp, err := r.doPost(r.Url, "fetchheaderext", []interface{}{r.Account, r.Password, "pending"})
    if err != nil {
        return nil, err
    }
    if rpcResp.Result != nil {
        var reply *GetBlockReplyPart
        err = json.Unmarshal(*rpcResp.Result, &reply)
        return reply, err
    }
    return nil, nil
}

func (r *RPCClient) GetBlockByHeight(height int64) (*GetBlockReply, error) {
    //params := []interface{}{fmt.Sprintf("0x%x", height), true}
    params := []interface{}{"-t", height}
    return r.getBlockBy("fetch-header", params)
}

Whenever I run that manually in the wallet it displays:

"result": {
    "bits": "7326472509313",
    "hash": "060d0f6157d08bb294ad30f97a2c15c821ff46236281f118d65576b9e4a0ba27",
    "merkle_tree_hash": "36936f36718e134e1eecaef05e66ebc4079811d8ee5a543f36d370335adc0801",
    "nonce": "0",
    "previous_block_hash": "10f4da59558fe41bab50a15864d1394462cd90836aecf52524f4cbce02a74a27",
    "time_stamp": "1520718416",
    "version": "1",
    "mixhash": "0",
    "number": "1011160",
    "transaction_count": "1"
}'

But, the code errors out with "json: cannot unmarshal string into Go value of type map[string]interface {}"

Can anyone help me figure this one out? I've been hours on trying to figure it out on my own.