Error is a special event, `type = Exception` and `name = error` by default.
`data` will be collected and set to `error stacktrace`.
```go
err:=errors.New("error")
// With default name as 'error'
cat.LogError(err)
// Or you can specify the name
cat.LogError(err,'error-name')
```
### Metric
We do aggregate every seconds.
For example, if you called count 3 times in one second (with the same name), we will just summarised the value of them and reported once to the server.
In case of `duration`, we use `averaged` value instead of `summarised` value.