问获取数据时的安卓捆绑ArrayOutOfBoundException

EN

java.lang.ArrayIndexOutOfBoundsException: length=0; index=4
        at android.util.ArrayMap.indexOf(ArrayMap.java:110)
        at android.util.ArrayMap.indexOfKey(ArrayMap.java:339)
        at android.util.ArrayMap.get(ArrayMap.java:381)
        at android.os.BaseBundle.getByte(BaseBundle.java:693)
        at android.os.Bundle.getByte(Bundle.java:579)
        at android.os.BaseBundle.getByte(BaseBundle.java:680)
        at android.os.Bundle.getByte(Bundle.java:566)
        at com.online.libcommunication.net.ThreadD.handleMessage(ThreadD.java:425)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:135)
        at android.os.HandlerThread.run(HandlerThread.java:61)

    @Override
    public boolean handleMessage(Message msg) {
        if(!this.isAlive()) {
            return false;
        }

        switch (msg.what)
        {
            case ThreadMessages.MSG_CMD : 
                bundle = msg.getData();
                byte modecmd = bundle.getByte("mode", (byte) 127); // <-- This is the line causing the exception
                // ...
                return true;
        }
    }

public void sendCommand(Bundle bundle,DPO dpo)
    {
        Message msg = mPHandler.obtainMessage();
        msg.what = ThreadMessages.MSG_CMD;
        msg.obj = dpo;
        msg.setData(bundle);
        mPHandler.sendMessage(msg);
    }

    bc.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
                mCmdBundle.clear();
                mCmdBundle.putByte("mode", (byte) 6);
                // + Other datas
                mActivity.getController().sendCommand(mCmdBundle, mDPO);
        }
    });