fix: support symbolic NotFoundResult

src/router.ts

@@ -299,11 +299,11 @@ export class Router<R extends AnyObject = EmptyObject> extends Resolver<R> {
         }
       })
       .then((result) => {
-        if (result != null && typeof result === 'object') {
+        if (result != null && (typeof result === 'object' || typeof result === 'symbol')) {
           // Actions like `() => import('my-view.js')` are not expected to
           // end the resolution, despite the result is not empty. Checking
           // the result with a whitelist of values that end the resolution.
-          if (result instanceof HTMLElement || 'redirect' in result || result === notFoundResult) {
+          if (result instanceof HTMLElement || result === notFoundResult || 'redirect' in result) {
             return result;
           }
         }

src/types.d.ts

@@ -1,6 +1,7 @@
 import type { EmptyObject, RequireAtLeastOne } from 'type-fest';
 import type { ResolutionError } from './resolver/resolver.js';
 import type { ChildrenCallback, IndexedParams, Params, ParamValue, PrimitiveParamValue } from './resolver/types.js';
+import type { NotFoundResult } from './resolver/utils.js';
 import type { Router } from './router.js';
 
 export type { ResolutionError, IndexedParams, Params, ParamValue, PrimitiveParamValue };
@@ -54,10 +55,6 @@ export interface NavigationTrigger {
   inactivate(): void;
 }
 
-export interface NotFoundResult {
-  notFoundResultBrand: never;
-}
-
 export type ResolutionResult<T> = T | NotFoundResult | null | undefined;
 
 export type ActionResult = ResolutionResult<HTMLElement | PreventResult | RedirectResult> | ResolutionResult<void>;