Fix web registry compatability bugs

api/resolver/resolver.go

@@ -2,9 +2,15 @@
 package resolver
 
 import (
+	"errors"
 	"net/http"
 )
 
+var (
+	ErrNotFound    = errors.New("not found")
+	ErrInvalidPath = errors.New("invalid path")
+)
+
 // Resolver resolves requests to endpoints
 type Resolver interface {
 	Resolve(r *http.Request) (*Endpoint, error)