Don''t fully fail bot when invalid price value is reached

closes #8300

freqtrade/exchange/exchange.py

@@ -1135,7 +1135,11 @@ class Exchange:
                           "sell" else (stop_price >= limit_rate))
         # Ensure rate is less than stop price
         if bad_stop_price:
-            raise OperationalException(
+            # This can for example happen if the stop / liquidation price is set to 0
+            # Which is possible if a market-order closes right away.
+            # The InvalidOrderException will bubble up to exit_positions, where it will be
+            # handled gracefully.
+            raise InvalidOrderException(
                 "In stoploss limit order, stop price should be more than limit price. "
                 f"Stop price: {stop_price}, Limit price: {limit_rate}, "
                 f"Limit Price pct: {limit_price_pct}"

freqtrade/freqtradebot.py

@@ -1021,12 +1021,16 @@ class FreqtradeBot(LoggingMixin):
         trades_closed = 0
         for trade in trades:
             try:
+                try:
+                    if (self.strategy.order_types.get('stoploss_on_exchange') and
+                            self.handle_stoploss_on_exchange(trade)):
+                        trades_closed += 1
+                        Trade.commit()
+                        continue
 
-                if (self.strategy.order_types.get('stoploss_on_exchange') and
-                        self.handle_stoploss_on_exchange(trade)):
-                    trades_closed += 1
-                    Trade.commit()
-                    continue
+                except InvalidOrderException as exception:
+                    logger.warning(
+                        f'Unable to handle stoploss on exchange for {trade.pair}: {exception}')
                 # Check if we can sell our current pair
                 if trade.open_order_id is None and trade.is_open and self.handle_trade(trade):
                     trades_closed += 1