Started with `localstack start` then navigated to `http://localhost:4569/shell`

Localstack version is `0.10.5`

![Screenshot from 2019-11-26 08-15-03](https://user-images.githubusercontent.com/57932946/69588919-24798700-1025-11ea-94d2-9cfb6dd20004.png)

Console log below, its all the same so I am just posting one

```2019-11-26T00:13:18:ERROR:localstack.services.generic_proxy: Error forwarding request: the JSON object must be str, bytes or bytearray, not NoneType Traceback (most recent call last):
  File "/opt/code/localstack/localstack/services/generic_proxy.py", line 240, in forward
    path=path, data=data, headers=forward_headers)
  File "/opt/code/localstack/localstack/services/dynamodb/dynamodb_listener.py", line 44, in forward_request
    data = json.loads(to_str(data))
  File "/usr/lib/python3.7/json/__init__.py", line 341, in loads
    raise TypeError(f'the JSON object must be str, bytes or bytearray, '
TypeError: the JSON object must be str, bytes or bytearray, not NoneType```

self._table_ttl_map = {}
    def forward_request(self, method, path, data, headers):
        if path.startswith('/shell'):
            return True
        if method == 'OPTIONS':
            return 200
        data = json.loads(to_str(data))
        ddb_client = aws_stack.connect_to_service('dynamodb')
        action = headers.get('X-Amz-Target')
        if random.random() < config.DYNAMODB_ERROR_PROBABILITY:
            throttled = ['%s.%s' % (ACTION_PREFIX, a) for a in THROTTLED_ACTIONS]
            if action in throttled:
                return error_response_throughput()
        ProxyListenerDynamoDB.thread_local.existing_item = None
        if action == '%s.CreateTable' % ACTION_PREFIX:
            
            table_names = ddb_client.list_tables()['TableNames']
            if to_str(data['TableName']) in table_names:
                return 200
        elif action in ('%s.PutItem' % ACTION_PREFIX, '%s.UpdateItem' % ACTION_PREFIX, '%s.DeleteItem' % ACTION_PREFIX):