hatpear.go
func Store(r *http.Request, err error) {
	errptr, ok := r.Context().Value(errorKey).(*error)
	if !ok {
		panic("hatpear: request not configured to store errors")
	}
	// check err after checking context to fail fast if unconfigured
	if err != nil {
		*errptr = err
	}
}
func Store(r *http.Request, err error) {
	errptr, ok := r.Context().Value(errorKey).(*error)
	if !ok {
		panic("hatpear: request not configured to store errors")
	}
	// check err after checking context to fail fast if unconfigured
	if err != nil {
		*errptr = err
	}
}
// Store stores an error into the request's context. It panics if the request
// was not configured to store errors.