Merge pull request #2655 from freqtrade/avoid_keyerror_backtest

Use first pair of pairlist to get fee

freqtrade/optimize/backtesting.py

@@ -65,7 +65,7 @@ class Backtesting:
         if config.get('fee'):
             self.fee = config['fee']
         else:
-            self.fee = self.exchange.get_fee()
+            self.fee = self.exchange.get_fee(symbol=self.config['exchange']['pair_whitelist'][0])
 
         if self.config.get('runmode') != RunMode.HYPEROPT:
             self.dataprovider = DataProvider(self.config, self.exchange)