# Buggy code
def update(self, order: Dict) -> None:
    """
    Updates this entity with amount and actual open/close rates.
    :param order: order retrieved by exchange.get_order()
    :return: None
    """
    order_type = order["type"]
    # Ignore open and cancelled orders
    if order["status"] == "open" or order["price"] is None:
        return

    logger.info("Updating trade (id=%s) ...", self.id)

    if order_type in ("market", "limit") and order["side"] == "buy":
        # Update open rate and actual amount
        self.open_rate = Decimal(order["price"])
        self.amount = Decimal(order["amount"])
        self.recalc_open_trade_price()
        logger.info("%s_BUY has been fulfilled for %s.", order_type.upper(), self)
        self.open_order_id = None
    elif order_type in ("market", "limit") and order["side"] == "sell":
        self.close(order["price"])
        logger.info("%s_SELL has been fulfilled for %s.", order_type.upper(), self)
    elif order_type == "stop_loss_limit":
        self.stoploss_order_id = None
        self.close_rate_requested = self.stop_loss
        logger.info("STOP_LOSS_LIMIT is hit for %s.", self)
        self.close(order["average"])
    else:
        raise ValueError(f"Unknown order type: {order_type}")
    cleanup()


# Traceback (Exception)
2020-02-20 22:47:28,025 - freqtrade - ERROR - Fatal exception!
Traceback (most recent call last):
File "/opt/tradebot/freqtrade/.env/lib/python3.7/site-packages/talib/__init__.py", line 20, in wrapper
for arg in chain(args, kwargs.values())
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/freqtrade/freqtrade/main.py", line 36, in main
return_code = args['func'](args)
File "/freqtrade/freqtrade/commands/optimize_commands.py", line 76, in start_hyperopt
hyperopt.start()
File "/freqtrade/freqtrade/optimize/hyperopt.py", line 488, in start
preprocessed = self.backtesting.strategy.tickerdata_to_dataframe(data)
File "/freqtrade/freqtrade/strategy/interface.py", line 448, in tickerdata_to_dataframe
for pair, pair_data in tickerdata.items()}
File "/freqtrade/freqtrade/strategy/interface.py", line 448, in <dictcomp>
for pair, pair_data in tickerdata.items()}
File "/freqtrade/freqtrade/strategy/interface.py", line 464, in advise_indicators
return self.populate_indicators(dataframe, metadata)
File "/freqtrade/user_data/strategies/MyDev.py", line 205, in populate_indicators
dataframe['mfi'] = ta.MFI(dataframe)
File "talib/_abstract.pxi", line 352, in talib._ta_lib.Function.__call__
File "talib/_abstract.pxi", line 383, in talib._ta_lib.Function.__call_function
File "/opt/tradebot/freqtrade/.env/lib/python3.7/site-packages/talib/__init__.py", line 24, in wrapper
return func(*args, **kwargs)
File "talib/_func.pxi", line 8454, in talib._ta_lib.MFI
Exception: volume is not double

# Fixed code
def update(self, order: Dict) -> None:
    """
    Updates this entity with amount and actual open/close rates.
    :param order: order retrieved by exchange.get_order()
    :return: None
    """
    order_type = order["type"]
    # Ignore open and cancelled orders
    if order["status"] == "open" or order["price"] is None:
        return

    logger.info("Updating trade (id=%s) ...", self.id)

    if order_type in ("market", "limit") and order["side"] == "buy":
        # Update open rate and actual amount
        self.open_rate = Decimal(order["price"])
        self.amount = Decimal(order["amount"])
        self.recalc_open_trade_price()
        logger.info("%s_BUY has been fulfilled for %s.", order_type.upper(), self)
        self.open_order_id = None
    elif order_type in ("market", "limit") and order["side"] == "sell":
        self.close(order["price"])
        logger.info("%s_SELL has been fulfilled for %s.", order_type.upper(), self)
    elif order_type in ("stop_loss_limit", "stop-loss"):
        self.stoploss_order_id = None
        self.close_rate_requested = self.stop_loss
        logger.info("%s is hit for %s.", order_type.upper(), self)
        self.close(order["average"])
    else:
        raise ValueError(f"Unknown order type: {order_type}")
    cleanup()