Apply suggestions from code review

Co-authored-by: wawyed <[email protected]>

downstream_projects.json

@@ -2,8 +2,8 @@
   "packageDir": "./dist",
   "projects": {
     "sample-app-angular": "https://github.com/ui-router/sample-app-angular.git",
-    "angular18": "./test-angular-versions/v19",
-    "angular18standalone": "./test-angular-versions/v19-standalone",
+    "angular19": "./test-angular-versions/v19",
+    "angular19standalone": "./test-angular-versions/v19-standalone",
     "typescript56": "./test-typescript-versions/typescript5.6"
   }
 }

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@uirouter/angular",
   "description": "State-based routing for Angular",
-  "version": "16.0.0",
+  "version": "15.0.0",
   "scripts": {
     "clean": "shx rm -rf lib lib-esm _bundles _doc dist",
     "compile": "npm run clean && ngc",