[BUG] [UI] White screen at login

[TLCFEM]

To reproduce:

1. Start the application.
2. Without logging in, click gear (top right corner), click theme, white screen appears.

TypeError
Cannot read property 'children' of undefined
Call Stack
 findNodes
  renderer.dev.js:261714:74
 filterNodesOfTree
  renderer.dev.js:261734:10
 InputPicker.renderDropdownMenu
  renderer.dev.js:249328:92
 InputPicker.render
  renderer.dev.js:249525:21
 finishClassComponent
  renderer.dev.js:193858:31
 updateClassComponent
  renderer.dev.js:193808:24
 beginWork
  renderer.dev.js:195446:16
 HTMLUnknownElement.callCallback
  renderer.dev.js:180318:14
 Object.invokeGuardedCallbackDev
  renderer.dev.js:180367:16
 invokeGuardedCallback
  renderer.dev.js:180429:31

[jeffvli]

Does it brick the application even when restarting?

[TLCFEM]

Basiclly the whole UI becomes a white screen and users cannot do anything with it. Restarting the application gives the normal login tab. See screenshot.

[jeffvli]

I ended up removing the top action bar when on the login screen since most of those shouldn't be touched until after logging in.