Absolutely.  We could have a struct type that defines the data structure for a mux error.  That struct could define a code int, a message body string, and whatever else we may need.  Then we'd just need 1 context key/value for any given error.  

What do you think about this:

```go
type MuxError struct {
    Code int
    Body string
    // Instead of having one specifically for allow headers, we can just put headers that will be added to the response, like code and body
    Headers map[string][]string
}
```

Thoughts?