Fix - getCoreSearchParams should not return undefined

[JohannesDoberer]

Fixes #2473
How to reproduce

Example config for simpledev:

{
              pathSegment: 'home2', 
              label: 'h2', 
              hideFromNav: false, 
              children: [
                {
                
                  pathSegment:'test',
                  label:'test',
                  loadingIndicator: {
                      enabled: false
                  },
                  viewUrl: 'microfrontend.html',
                  clientPermissions:{
                    urlParameters:{
                      q:{
                        write: true,
                        read: true
                      }
                    }
                  }
                },
                {
                  pathSegment:'test2',
                  label:'test2',
                  loadingIndicator: {
                      enabled: false
                  },
                  viewUrl: 'microfrontend2.html'
                }
              ]
          }

• navigate without sync from test to test2
  LuigiClient.linkManager().withoutSync().navigate('/home2/test2')
• LuigiClient.getCoreSearchParams() should return an empty object instead of undefined

[ndricimrr]

Works as expected 👍