Fix big number accuracy

lib/packets/packet.js

@@ -222,9 +222,8 @@ class Packet {
         return word1 * 0x100000000 + word0;
       }
       res = new Long(word0, word1, !signed); // Long need unsigned
-      const resNumber = res.toNumber();
       const resString = res.toString();
-      res = resNumber.toString() === resString ? resNumber : resString;
+      res = res.greaterThan(Number.MAX_SAFE_INTEGER) ? res.toNumber() : resString;
       return bigNumberStrings ? resString : res;
     }
     // eslint-disable-next-line no-console
@@ -425,7 +424,7 @@ class Packet {
     return StringParser.decode(
       this.buffer,
       encoding,
-      this.offset - len, 
+      this.offset - len,
       this.offset
     );
   }
@@ -456,15 +455,12 @@ class Packet {
     if (supportBigNumbers) {
       if (numDigits >= 15) {
         str = this.readString(end - this.offset, 'binary');
-        result = parseInt(str, 10);
-        if (result.toString() === str) {
-          return sign * result;
-        }
-        return sign === -1 ? `-${str}` : str;
-      }
-      if (numDigits > 16) {
-        str = this.readString(end - this.offset);
-        return sign === -1 ? `-${str}` : str;
+        str = sign === -1 ? `-${str}` : str;
+        result = Long.fromString(str, false, 10);
+        if (result.greaterThan(Number.MAX_SAFE_INTEGER) || result.lessThan(Number.MIN_SAFE_INTEGER)) {
+          return result;
+        } 
+        return result.toNumber();
       }
     }
     if (this.buffer[this.offset] === plus) {