Fix mypy type errors

freqtrade/optimize/optimize_reports.py

@@ -165,7 +165,7 @@ def generate_tag_metrics(tag_type: str,
         tabular_data.append(_generate_result_line(results, starting_balance, 'TOTAL'))
         return tabular_data
     else:
-        return None
+        return []
 
 
 def _generate_tag_result_line(result: DataFrame, starting_balance: int, first_column: str) -> Dict:

freqtrade/persistence/models.py

@@ -861,7 +861,7 @@ class Trade(_DECL_BASE, LocalTrade):
         ]
 
     @staticmethod
-    def get_buy_tag_performance(pair: str) -> List[Dict[str, Any]]:
+    def get_buy_tag_performance(pair: Optional[str]) -> List[Dict[str, Any]]:
         """
         Returns List of dicts containing all Trades, based on buy tag performance
         Can either be average for all pairs or a specific pair provided
@@ -900,7 +900,7 @@ class Trade(_DECL_BASE, LocalTrade):
         ]
 
     @staticmethod
-    def get_sell_reason_performance(pair: str) -> List[Dict[str, Any]]:
+    def get_sell_reason_performance(pair: Optional[str]) -> List[Dict[str, Any]]:
         """
         Returns List of dicts containing all Trades, based on sell reason performance
         Can either be average for all pairs or a specific pair provided
@@ -938,7 +938,7 @@ class Trade(_DECL_BASE, LocalTrade):
         ]
 
     @staticmethod
-    def get_mix_tag_performance(pair: str) -> List[Dict[str, Any]]:
+    def get_mix_tag_performance(pair: Optional[str]) -> List[Dict[str, Any]]:
         """
         Returns List of dicts containing all Trades, based on buy_tag + sell_reason performance
         Can either be average for all pairs or a specific pair provided

freqtrade/rpc/rpc.py

@@ -689,7 +689,7 @@ class RPC:
         [x.update({'profit': round(x['profit'] * 100, 2)}) for x in pair_rates]
         return pair_rates
 
-    def _rpc_buy_tag_performance(self, pair: str) -> List[Dict[str, Any]]:
+    def _rpc_buy_tag_performance(self, pair: Optional[str]) -> List[Dict[str, Any]]:
         """
         Handler for buy tag performance.
         Shows a performance statistic from finished trades
@@ -699,7 +699,7 @@ class RPC:
         [x.update({'profit': round(x['profit'] * 100, 2)}) for x in buy_tags]
         return buy_tags
 
-    def _rpc_sell_reason_performance(self, pair: str) -> List[Dict[str, Any]]:
+    def _rpc_sell_reason_performance(self, pair: Optional[str]) -> List[Dict[str, Any]]:
         """
         Handler for sell reason performance.
         Shows a performance statistic from finished trades
@@ -709,7 +709,7 @@ class RPC:
         [x.update({'profit': round(x['profit'] * 100, 2)}) for x in sell_reasons]
         return sell_reasons
 
-    def _rpc_mix_tag_performance(self, pair: str) -> List[Dict[str, Any]]:
+    def _rpc_mix_tag_performance(self, pair: Optional[str]) -> List[Dict[str, Any]]:
         """
         Handler for mix tag (buy_tag + sell_reason) performance.
         Shows a performance statistic from finished trades