Merge pull request #279 from adam-golab/master

Fix for the "Storybook preview hooks can only be called inside decorators and story functions." error

src/index.tsx

@@ -1,15 +1,14 @@
-import React from 'react';
-import { addons } from '@storybook/preview-api';
+import { addons, useState, useEffect } from '@storybook/preview-api';
 import { DARK_MODE_EVENT_NAME } from './constants';
 import { store } from './Tool';
 
 /**
  * Returns the current state of storybook's dark-mode
  */
 export function useDarkMode(): boolean {
-  const [isDark, setIsDark] = React.useState(store().current === 'dark');
+  const [isDark, setIsDark] = useState(store().current === 'dark');
 
-  React.useEffect(() => {
+  useEffect(() => {
     const chan = addons.getChannel();
     chan.on(DARK_MODE_EVENT_NAME, setIsDark);
     return () => chan.off(DARK_MODE_EVENT_NAME, setIsDark);