# Buggy code
def handle_trade(self, trade: Trade) -> bool:
    """
    Sells the current pair if the threshold is reached and updates the trade record.
    :return: True if trade has been sold, False otherwise
    """
    if not trade.is_open:
        raise DependencyException(f"Attempt to handle closed trade: {trade}")

    logger.debug("Handling %s ...", trade)

    (buy, sell) = (False, False)

    config_ask_strategy = self.config.get("ask_strategy", {})

    if config_ask_strategy.get("use_sell_signal", True) or config_ask_strategy.get(
        "ignore_roi_if_buy_signal"
    ):
        (buy, sell) = self.strategy.get_signal(
            trade.pair,
            self.strategy.ticker_interval,
            self.dataprovider.ohlcv(trade.pair, self.strategy.ticker_interval),
        )

    if config_ask_strategy.get("use_order_book", False):
        logger.info("Using order book for selling...")
        # logger.debug('Order book %s',orderBook)
        order_book_min = config_ask_strategy.get("order_book_min", 1)
        order_book_max = config_ask_strategy.get("order_book_max", 1)

        order_book = self.exchange.get_order_book(trade.pair, order_book_max)

        for i in range(order_book_min, order_book_max + 1):
            order_book_rate = order_book["asks"][i - 1][0]
            logger.info("  order book asks top %s: %0.8f", i, order_book_rate)
            sell_rate = order_book_rate

            if self._check_and_execute_sell(trade, sell_rate, buy, sell):
                return True

    else:
        logger.debug("checking sell")
        sell_rate = self.get_sell_rate(trade.pair, True)
        if self._check_and_execute_sell(trade, sell_rate, buy, sell):
            return True

    logger.debug("Found no sell signal for %s.", trade)
    return False


# 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 handle_trade(self, trade: Trade) -> bool:
    """
    Sells the current pair if the threshold is reached and updates the trade record.
    :return: True if trade has been sold, False otherwise
    """
    if not trade.is_open:
        raise DependencyException(f"Attempt to handle closed trade: {trade}")

    logger.debug("Handling %s ...", trade)

    (buy, sell) = (False, False)

    config_ask_strategy = self.config.get("ask_strategy", {})

    if config_ask_strategy.get("use_sell_signal", True) or config_ask_strategy.get(
        "ignore_roi_if_buy_signal"
    ):
        (buy, sell) = self.strategy.get_signal(
            trade.pair,
            self.strategy.ticker_interval,
            self.dataprovider.ohlcv(trade.pair, self.strategy.ticker_interval),
        )

    if config_ask_strategy.get("use_order_book", False):
        logger.debug(f"Using order book for selling {trade.pair}...")
        # logger.debug('Order book %s',orderBook)
        order_book_min = config_ask_strategy.get("order_book_min", 1)
        order_book_max = config_ask_strategy.get("order_book_max", 1)

        order_book = self.exchange.get_order_book(trade.pair, order_book_max)

        for i in range(order_book_min, order_book_max + 1):
            order_book_rate = order_book["asks"][i - 1][0]
            logger.debug("  order book asks top %s: %0.8f", i, order_book_rate)
            sell_rate = order_book_rate

            if self._check_and_execute_sell(trade, sell_rate, buy, sell):
                return True

    else:
        logger.debug("checking sell")
        sell_rate = self.get_sell_rate(trade.pair, True)
        if self._check_and_execute_sell(trade, sell_rate, buy, sell):
            return True

    logger.debug("Found no sell signal for %s.", trade)
    return False