Expanding and Collapsing the Sidebar is not working

[oruburos]

Nature of issue?

• Found a bug

Details about the bug:

• Web browser and version:

Google Chrome	84.0.4147.135 (Official Build) (64-bit) (cohort: Stable)
Revision	c42bd09b3f24da1698d71d3b4f57402137163566-refs/branch-heads/4147@{#1102}

• Operating System: OS | Windows 10 OS Version 1909 (Build 18363.1016)

• Steps to reproduce this bug:
  Trying to expand the sidebar doesn't work

[catarak]

Thank you! This was introduced in #1544 when the Editor was refactored to use react-redux.