Documentation examples for Custom Menu throws error

[elsni]

The example code from the documentation page:
https://marmelab.com/react-admin/Theming.html#using-a-custom-menu

leads to an error:

Error: Expected ref to be a function, a string, an object returned by React.createRef(), or null.

React-admin version: 3.2.1

Module../src/index.js
C:/Users/elsneste/source/eptw/src/index.js:7
4 | import App from './App';
5 | import * as serviceWorker from './serviceWorker';
6 |

7 | ReactDOM.render(, document.getElementById('root'));
8 |
9 | // If you want your app to work offline and load faster, you can change
10 | // unregister() to register() below. Note this comes with some pitfalls.
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webpack_require
C:/Users/elsneste/source/eptw/webpack/bootstrap:785
782 | };
783 |
784 | // Execute the module function
785 | modules[moduleId].call(module.exports, module, module.exports, hotCreateRequire(moduleId));
| ^ 786 |
787 | // Flag the module as loaded
788 | module.l = true;
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fn
C:/Users/elsneste/source/eptw/webpack/bootstrap:150
147 | );
148 | hotCurrentParents = [];
149 | }
150 | return webpack_require(request);
| ^ 151 | };
152 | var ObjectFactory = function ObjectFactory(name) {
153 | return {
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1
http://localhost:3000/static/js/main.chunk.js:6075:18
webpack_require
C:/Users/elsneste/source/eptw/webpack/bootstrap:785
782 | };
783 |
784 | // Execute the module function
785 | modules[moduleId].call(module.exports, module, module.exports, hotCreateRequire(moduleId));
| ^ 786 |
787 | // Flag the module as loaded
788 | module.l = true;
View compiled
checkDeferredModules
C:/Users/elsneste/source/eptw/webpack/bootstrap:45
42 | }
43 | if(fulfilled) {
44 | deferredModules.splice(i--, 1);
45 | result = webpack_require(webpack_require.s = deferredModule[0]);
| ^ 46 | }
47 | }
48 |
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Array.webpackJsonpCallback [as push]
C:/Users/elsneste/source/eptw/webpack/bootstrap:32
29 | deferredModules.push.apply(deferredModules, executeModules || []);
30 |
31 | // run deferred modules when all chunks ready
32 | return checkDeferredModules();
| ^ 33 | };
34 | function checkDeferredModules() {
35 | var result;
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[fzaninotto]

That's because your resources have no icon. I'll update the documentation to avoid that gotcha.