@@ -21,6 +21,18 @@ providers  []ResourceProvider
 	corsOrigin string
 }
 
+var (
+	ErrMissingResourceParameter = ihttp.NewError(
+		"Missing resource parameter",
+		http.StatusBadRequest,
+	)
+	ErrFailedToEncodeResponse = ihttp.NewError(
+		"Failed to encode webfinger response",
+		http.StatusInternalServerError,
+	)
+	ErrNotFound = ihttp.NewError("Resource not found", http.StatusNotFound)
+)
+
 type Option func(*Service)
 
 func WithCORSOrigin(origin string) Option {
@@ -50,7 +62,7 @@
 func (s *Service) HandleFunc(w http.ResponseWriter, r *http.Request) ihttp.Error {
 	resource := r.URL.Query().Get("resource")
 	if resource == "" {
-		return ihttp.BadRequest("Missing resource parameter", nil)
+		return ErrMissingResourceParameter
 	}
 
 	for _, provider := range s.providers {
@@ -62,12 +74,12 @@ w.Header().Add("Access-Control-Allow-Origin", s.corsOrigin)
 			}
 
 			if err := json.NewEncoder(w).Encode(provider.GetIdentityResource()); err != nil {
-				return ihttp.InternalServerError("Failed to encode webfinger response", err)
+				return ErrFailedToEncodeResponse.WithCause(err)
 			}
 
 			return nil
 		}
 	}
 
-	return ihttp.NotFound("Resource not found")
+	return ErrNotFound
 }