title: Types of parameters 'action' and 'action' are incompatible
body: <p>I'm just starting with react redux with Typescript (v 2.6.1) and I have been working on a little app from the VS 2017 boilerplate. At my fifth View, I see that for some reason I have problems in creating actions. Basically in the code below that is a very simplified code, that should work very easily, if I remove the multiplier in the Multiply action works but when I add the multiplier doesn't. I can't figure it out.</p>
  
  <p>Trying to simplify and fix it, I see that it's not even working the following code, which should be pretty straighforward.</p>
  
  <pre><code>import { AppThunkAction } from "ClientApp/store";
  import { Action, Reducer } from 'redux';
  import { fetch, addTask } from 'domain-task';
  import update from 'immutability-helper';
  
  // The top-level state object
  export interface CompoundState {
      value: number,
  }
  
  export interface AddAction  {
      type: 'ADD_ACTION',
      addend:number
  }
  
  export interface MultiplyAction {
      type: 'MULTIPLY_ACTION',
      multiplier:number
  }
  
  type KnownAction = AddAction | MultiplyAction
  export const actionCreators = {
      add: (addend): AppThunkAction&lt;AddAction&gt; =&gt; (dispatch, getState) =&gt; {
          dispatch({ type: 'ADD_ACTION', addend: addend })
      },
      multiply: (multiplier): AppThunkAction&lt;MultiplyAction&gt; =&gt; (dispatch, getState) =&gt; {
          dispatch({ type: 'MULTIPLY_ACTION', multiplier: multiplier })
      },
  }
  
  const unloadedState: CompoundState =
  {
      value: 0,
  };
  export const reducer: Reducer&lt;CompoundState&gt; = (state: CompoundState, action: KnownAction) =&gt; {
  
      switch (action.type) {
          case 'ADD_ACTION':
              return update(state, {
                  value: {
                      $set: state.value + action.addend
                  }
              });
          case 'MULTIPLY_ACTION':
              return update(state, {
                  value: {
                      $set: state.value * action.multiplier
                  }
              });
  
      }
      return state || unloadedState;
  };
  </code></pre>
  
  <p>What do you think?</p>