fix: shidenggui#468 Update judgment conditions to avoid program crashes

the condition branch I just modified have a bug when program is in univisal_ths-joinquant mode. bug details references shidenggui#468,  so I update judgment conditions to avoid program crashes

easytrader/follower.py

@@ -278,7 +278,7 @@ def _execute_trade_cmd(
 
             # check price
             price = trade_cmd["price"]
-            if not self._is_number(price) or price <= 0:
+            if not (self._is_number(price) and price > 0):
                 logger.warning(
                     "策略 [%s] 指令(股票: %s 动作: %s 数量: %s 价格: %s)超时，指令产生时间: %s 当前时间: %s, 价格无效 , 被丢弃",
                     trade_cmd["strategy_name"],