index column menu not working

Nothing happens when I click on the menu button. I tried this on Chrome with and without extensions.

Looking at Chrome's Developer Tools, I see this error:

```
Uncaught (in promise) Error: Canceled
at t.dispose (future.js:155)
at default.js:893
at Map.forEach ()
at e._clearState (default.js:892)
at e.handleRestart (default.js:494)
at default.js:1284
at Object.i [as each] (iter.js:60)
at Object.f [as restartKernel] (default.js:1282)
at e.restart (default.js:487)
at clientsession.js:612
at
```

and:

```
Uncaught (in promise) TypeError: Cannot read property 'replace' of null
at nt (index.js:21626)
at x.fn.init. (index.js:16805)
at index.js:22204
at Function.map (index.js:520)
at mt (index.js:22203)
at de (index.js:19079)
at fe (index.js:19122)
at qe (index.js:20304)
at I (index.js:16878)
at l (index.js:21907)
at lt (index.js:21991)
at HTMLTableElement. (index.js:16887)
at Function.each (index.js:431)
at x.fn.init.each (index.js:226)
at x.fn.init.i [as dataTable] (index.js:16452)
at x.fn.init.e.fn.DataTable (index.js:30652)
at y.doCreateTable (index.js:79073)
at y.init (index.js:78249)
at y.run (index.js:79952)
at initTableDisplay (index.js:77605)
at index.js:77562
at
Uncaught (in promise) TypeError: Cannot read property 'replace' of null
at nt (index.js:21626)
at x.fn.init. (index.js:16805)
at index.js:22204
at Function.map (index.js:520)
at mt (index.js:22203)
at de (index.js:19079)
at fe (index.js:19122)
at qe (index.js:20304)
at I (index.js:16878)
at l (index.js:21907)
at lt (index.js:21991)
at HTMLTableElement. (index.js:16887)
at Function.each (index.js:431)
at x.fn.init.each (index.js:226)
at x.fn.init.i [as dataTable] (index.js:16452)
at x.fn.init.e.fn.DataTable (index.js:30652)
at y.doCreateTable (index.js:79073)
at y.init (index.js:78249)
at y.run (index.js:79952)
at initTableDisplay (index.js:77605)
at index.js:77562
at
```