Fix rounding error when tag is not numeric.

Author: kjpou1

backtesting/backtesting.py

@@ -49,6 +49,7 @@ class Strategy(metaclass=ABCMeta):
     `backtesting.backtesting.Strategy.next` to define
     your own strategy.
     """
+
     def __init__(self, broker, data, params):
         self._indicators = []
         self._broker: _Broker = broker
@@ -291,6 +292,7 @@ class _Orders(tuple):
     """
     TODO: remove this class. Only for deprecation.
     """
+
     def cancel(self):
         """Cancel all non-contingent (i.e. SL/TP) orders."""
         for order in self:
@@ -318,6 +320,7 @@ class Position:
         if self.position:
             ...  # we have a position, either long or short
     """
+
     def __init__(self, broker: '_Broker'):
         self.__broker = broker
 
@@ -382,6 +385,7 @@ class Order:
     [filled]: https://www.investopedia.com/terms/f/fill.asp
     [Good 'Til Canceled]: https://www.investopedia.com/terms/g/gtc.asp
     """
+
     def __init__(self, broker: '_Broker',
                  size: float,
                  limit_price: Optional[float] = None,
@@ -415,7 +419,7 @@ def __repr__(self):
                                                  ('tp', self.__tp_price),
                                                  ('contingent', self.is_contingent),
                                                  ('tag', self.__tag),
-                                             ) if value is not None))
+                                             ) if value is not None and isinstance(value, Number)))
 
     def cancel(self):
         """Cancel the order."""
@@ -528,6 +532,7 @@ class Trade:
     When an `Order` is filled, it results in an active `Trade`.
     Find active trades in `Strategy.trades` and closed, settled trades in `Strategy.closed_trades`.
     """
+
     def __init__(self, broker: '_Broker', size: int, entry_price: float, entry_bar, tag):
         self.__broker = broker
         self.__size = size
@@ -1021,6 +1026,7 @@ class Backtest:
     instance, or `backtesting.backtesting.Backtest.optimize` to
     optimize it.
     """
+
     def __init__(self,
                  data: pd.DataFrame,
                  strategy: Type[Strategy],