[TV] refactor is_first_trading_mode_on_this_matrix

Author: GuillaumeDSM

Trading/Mode/trading_view_signals_trading_mode/trading_view_signals_trading.py

@@ -209,8 +209,8 @@ def is_compatible_trading_type(cls, parsed_signal: dict, trading_type: trading_e
 
     def _log_error_message_if_relevant(self, parsed_data: dict, signal_data: str):
         # only log error messages on one TradingViewSignalsTradingMode instance to avoid logging errors multiple times
-        all_trading_modes = trading_modes.get_trading_modes_of_this_type_on_this_matrix(self)
-        if all_trading_modes and all_trading_modes[0] is self:
+        if self.is_first_trading_mode_on_this_matrix():
+            all_trading_modes = trading_modes.get_trading_modes_of_this_type_on_this_matrix(self)
             # Can log error message: this is the first trading mode on this matrix. 
             # Each is notified by signals and only this one will log errors to avoid duplicating logs
             if not any(