I got the following error while refactoring the app:
main.ts:21 Error: NG0200: Circular dependency in DI detected for ApplicationRef. Find more at https://angular.io/errors/NG0200
at throwCyclicDependencyError (core.js:216)
at R3Injector.hydrate (core.js:11433)
at R3Injector.get (core.js:11256)
at injectInjectorOnly (core.js:4751)
at Module.ɵɵinject (core.js:4755)
at Object.Config_Factory [as factory] (config.ts:7)
at R3Injector.hydrate (core.js:11437)
at R3Injector.get (core.js:11256)
at injectInjectorOnly (core.js:4751)
at Module.ɵɵinject (core.js:4755)
But I haven't found any circular dependencies. What else can be the cause?