[TradingView] fix KeyError

Author: GuillaumeDSM

Services/Services_bases/trading_view_service/trading_view.py

@@ -135,7 +135,7 @@ async def prepare(self) -> None:
             if self.token is None:
                 self.token = self.get_default_value()[services_constants.CONFIG_TRADING_VIEW_TOKEN]
             if self.use_email_alert is None:
-                self.use_email_alert = self.get_default_value()[services_constants.CONFIG_TRADING_VIEW_USE_EMAIL_ALERTS]
+                self.use_email_alert = self.get_default_value().get(services_constants.CONFIG_TRADING_VIEW_USE_EMAIL_ALERTS, False)
             # save new values into config file
             updated_config = {
                 services_constants.CONFIG_REQUIRE_TRADING_VIEW_TOKEN: self.requires_token,