tslint spik default context check

Author: zombieJ

src/MentionsContext.ts

@@ -1,3 +1,4 @@
+/* tslint:disable: no-object-literal-type-assertion */
 import createReactContext, { Context } from '@ant-design/create-react-context';
 import * as React from 'react';
 import { OptionProps } from './Option';
@@ -10,7 +11,10 @@ export interface MentionsContextProps {
   onFocus: () => void;
 }
 
-const MentionsContext: Context<MentionsContextProps | null> = createReactContext(null);
+// We will never use default, here only to fix TypeScript warning
+const MentionsContext: Context<MentionsContextProps> = createReactContext(
+  {} as MentionsContextProps,
+);
 
 export const MentionsContextProvider = MentionsContext.Provider;
 export const MentionsContextConsumer = MentionsContext.Consumer;