修复processAmount的bug

kucoinCollector.js

@@ -161,15 +161,17 @@ class BiboxCollector extends BaseCollector{
   }
   processAmount(fromCurrency,toCurrency,amount){
     //有可能会由于数值过小，传进来的amount被表示为科学计数法法
+    const symbolDetail = this._getSymbolDetail(fromCurrency,toCurrency);
+    const currency = symbolDetail.coinType;
     let tradePrecision = 4;
-    const coin = coinInfoMap[toCurrency];
+    const coin = coinInfoMap[currency];
     if(coin){
       tradePrecision = coin['tradePrecision'] || 4;
     }
     const amountStr = parseFloat(amount).toFixed(10);
     const nums = amountStr.split('.');
     if(nums.length ===2 && nums[1].length>tradePrecision){
-      return nums[0]+"."+nums[1].slice(0,4);
+      return nums[0]+"."+nums[1].slice(0,tradePrecision);
     }
     return amount;
   }