#248 Add union overload to ThunkDispatch (#255)

* #248 Add union overload to ThunkDispatch

See discussion in #248 and microsoft/TypeScript#14107. Without this explicit overload, TypeScript is unable to figure out that the function can be called with an argument of type `T|ThunkAction<...>`.

* Merge ThunkDispatch union overload with renamed type parameters

Co-Authored-By: Tim Dorr <[email protected]>

Author: MiyamotoSatoshi

index.d.ts

@@ -26,6 +26,12 @@ export interface ThunkDispatch<
     thunkAction: ThunkAction<TReturnType, TState, TExtraThunkArg, TBasicAction>
   ): TReturnType;
   <A extends TBasicAction>(action: A): A;
+  // This overload is the union of the two above (see TS issue #14107).
+  <TReturnType, TAction extends TBasicAction>(
+    action:
+      | TAction
+      | ThunkAction<TReturnType, TState, TExtraThunkArg, TBasicAction>
+  ): TAction | TReturnType;
 }
 
 /**