Combination of redirecting under a primary route and route guarding a sibling route under a named outlet causes NG04013

[pfeileon]

Which @angular/* package(s) are the source of the bug?

router

Is this a regression?

No

Description

On a route with two children with an empty path, one on a named outlet, the other with a child-redirect, the router seems to activate (and never deactivate?) the named outlet if a canMatch (or canActivate) guard returns false.

This causes the issue that after the initial navigation ("/items/:id") which successfully redirects ("items/:id/main"), every other parallel navigation throws the mentioned error.

If the guard returns true, everything works as expected.

Component/route hierarchy (I'm mixing component and route hierarchy for simplicity):

RootComponent
  primary outlet> someLazyRoutes => moreLazyRoutes => ListComponent => routesWithIssues
  named outlet> AsideComponent

export const routesWithIssues = [
  {
    path: ':id'
    children: [
      {
        path: '',
        loadComponent: () => ItemComponent,
        // initial redirection works,
        // navigating to or deep linking to other routes on the same level as "main" causes the error
        children: [
          // Removing this redirection route solves the issue (but has the side-effect that it doesn't redirect, obviously)
          {path: '', pathMatch: 'full', redirectTo: 'main'},
          ...otherTabbedChildRoutesIncludingMain
        ]
      },
      {
        path: '',
        outlet: 'aside',
        // If the guard returns true, no error occurrs.
        // (Strange sidenote: only defining `canActivate` breaks routing completely without an error message,
        // i.e. only the RootComponent is loaded)
        canMatch: [() => false],
        loadComponent: () => AsideComponent
      },
    ]
  }
] as Routes

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

Error: NG04013: Cannot activate an already activated outlet
    at RouterOutlet.activateWith (router.mjs:2552:19)
    at ActivateRoutes.activateRoutes (router.mjs:3146:40)
    at router.mjs:3097:18
    at Array.forEach (<anonymous>)
    at ActivateRoutes.activateChildRoutes (router.mjs:3096:29)
    at ActivateRoutes.activateRoutes (router.mjs:3113:22)
    at router.mjs:3097:18
    at Array.forEach (<anonymous>)
    at ActivateRoutes.activateChildRoutes (router.mjs:3096:29)
    at ActivateRoutes.activateRoutes (router.mjs:3117:22)

Please provide the environment you discovered this bug in (run ng version)

Angular CLI: 17.3.8
Node: 20.14.0
Package Manager: npm 10.7.0
OS: linux x64

Angular: 17.3.10
... animations, cdk, common, compiler, compiler-cli, core, forms
... material, platform-browser, platform-browser-dynamic, router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1703.8
@angular-devkit/build-angular   17.3.8
@angular-devkit/core            17.3.8
@angular-devkit/schematics      17.3.8
@angular/cli                    17.3.8
@schematics/angular             17.3.8
rxjs                            7.8.1
typescript                      5.3.3
zone.js                         0.14.6

Anything else?

I experimented with trying to deactivate the outlet imperatively, but it didn't work.