Remove unreachable code

Author: Maciej Mucha

decoder.go

@@ -116,11 +116,7 @@ func (d *decoder) parseMapData() {
 					// no need to check for error, it will always pass
 					// as we have done the checking to ensure
 					// the value is a number ahead of time.
-					var err error
-					ke.ivalue, err = strconv.Atoi(ke.value)
-					if err != nil {
-						ke.ivalue = -1
-					}
+					ke.ivalue, _ = strconv.Atoi(ke.value)
 
 					if ke.ivalue > rd.sliceLen {
 						rd.sliceLen = ke.ivalue