title: Redux - createStore. Argument of type is not assignable to parameter of type 'DeepPartial<any>'
body: <p>When I start compilation I always gets a stack error. Which says that my <code>initialState</code> in <code>store</code> is broken or someone else. Moreover, my app is compile normally if I just cut off <code>initialState</code> prop from <code>store</code>, but it's not a good solutions. </p>
  
  <p>I also admit that it's work normally on <code>.js</code> file version of the app. Seem like redux have some problems with the TypeScript.</p>
  
  <p>Error:</p>
  
  <blockquote>
    <p>TS2345: Argument of type '{ titleSwitch: string; }' is not assignable
    to parameter of type 'DeepPartial'. Property 'titleSwitch' is
    incompatible with index signature. Type 'string' is not assignable to
    type 'DeepPartial'.</p>
  </blockquote>
  
  <p>My part of code:</p>
  
  <pre><code>import { createStore } from 'redux'
  import reducer from './reducers'
  
  const initialState = {
    titleSwitch: false
  }
  
  const store = () =&gt; {
    return createStore(
      reducer,
      initialState // TS Error
    )
  }
  </code></pre>
  
  <p>Tested on:</p>
  
  <pre><code>"redux": "^4.0.0",
  "typescript": "^3.1.1",
  "webpack": "^4.16.5"
  </code></pre>