Cannot read property 'visitExpression' of undefined

In my angular app at the startup point I'm facing this error:

Cannot read property visitExpression of undefined

What could be the problem?

In my case, it was duplicate , in the Routes array in app.routing.ts.

You can use ,[\s]*, as a Regular Expression search query to find it in your routes to find two commas with (0 to many) white spaces in between them.

It was ',' in my case in app.module.ts file.

imports: [
    BrowserModule,
    **AppRoutingModule,,**
    HttpClientModule,

Changed it to:

imports: [
    BrowserModule,
    **AppRoutingModule,**
    HttpClientModule,

In my case, it was components with empty selectors.