title: Typescript react-redux configuring store error
body: <p>This is my code:</p>
  <pre><code>interface IState {
    userData: {
      name: string
      age: number
    }
    // companyData: {},
    // websiteData: {}
  }
  export const initialState: IState = {
    userData: {
      name: &quot;Mark&quot;,
      age: 30
    }
    // companyData: {},
    // websiteData: {},
  } 
  
  const mainReducer = combineReducers({
    userData: userReducer
    // companyData: companyDataReducer,
    // websiteData: websiteDataReducer,
  });
  
  const configureStore = () =&gt;
    createStore(
      mainReducer,
      initialState,
      composeWithDevTools(applyMiddleware(thunk))
    );
  
  export default configureStore;
  
  </code></pre>
  <p>it generates this error which I do not understand:</p>
  <p>Argument of type 'IState' is not assignable to parameter of type '{ userData?: { userData: any; } | undefined; }'.
  Types of property 'userData' are incompatible.
  Property 'userData' is missing in type '{ name: string; age: number; }' but required in type '{ userData: any; }'.</p>