[BUGFIX release] Ensure query param only link-to's work in error states.

packages/@ember/-internals/glimmer/lib/components/link-to.ts

@@ -487,7 +487,9 @@ if (EMBER_GLIMMER_ANGLE_BRACKET_BUILT_INS) {
     _currentRouterState: alias('_routing.currentState'),
     _targetRouterState: alias('_routing.targetState'),
 
-    _route: computed('route', '_currentRoute', function computeLinkToComponentRoute(this: any) {
+    _route: computed('route', '_currentRouterState', function computeLinkToComponentRoute(
+      this: any
+    ) {
       let { route } = this;
       return route === UNDEFINED ? this._currentRoute : route;
     }),

packages/@ember/-internals/glimmer/tests/integration/components/link-to/query-params-angle-test.js

@@ -240,6 +240,77 @@ if (EMBER_GLIMMER_ANGLE_BRACKET_BUILT_INS) {
         });
       }
 
+      ['@test generates proper href for `LinkTo` with no @route after transitioning to an error route GH#17963'](
+        assert
+      ) {
+        this.router.map(function() {
+          this.route('bad');
+        });
+
+        this.add(
+          'controller:application',
+          Controller.extend({
+            queryParams: ['baz'],
+          })
+        );
+
+        this.add(
+          'route:bad',
+          Route.extend({
+            model() {
+              throw new Error('bad!');
+            },
+          })
+        );
+
+        this.addTemplate('error', `Error: {{model.message}}`);
+
+        this.addTemplate(
+          'application',
+          `
+          <LinkTo id="bad-link" @route="bad">
+            Bad
+          </LinkTo>
+
+          <LinkTo id="good-link" @query={{hash baz='lol'}}>
+            Good
+          </LinkTo>
+
+          {{outlet}}
+          `
+        );
+
+        return this.visit('/')
+          .then(async () => {
+            assert.equal(this.$('#good-link').length, 1, 'good-link should be in the DOM');
+            assert.equal(this.$('#bad-link').length, 1, 'bad-link should be in the DOM');
+
+            let goodLink = this.$('#good-link');
+            assert.equal(goodLink.attr('href'), '/?baz=lol');
+
+            return this.visit('/bad');
+          })
+          .then(() => {
+            assert.equal(this.$('#good-link').length, 1, 'good-link should be in the DOM');
+            assert.equal(this.$('#bad-link').length, 1, 'bad-link should be in the DOM');
+
+            let goodLink = this.$('#good-link');
+            // should still be / because we never entered /bad (it errored before being fully entered)
+            // and error states do not get represented in the URL, so we are _effectively_ still
+            // on /
+            assert.equal(goodLink.attr('href'), '/?baz=lol');
+
+            runTask(() => this.click('#good-link'));
+
+            let applicationController = this.getController('application');
+            assert.deepEqual(
+              applicationController.getProperties('baz'),
+              { baz: 'lol' },
+              'index controller QP properties updated'
+            );
+          });
+      }
+
       ['@test supplied QP properties can be bound'](assert) {
         this.addTemplate(
           'index',