ModeHandler: error handling key=<C-w>, err=TypeError: Cannot read property 'selections' of undefined

[kenorb]

Describe the bug

The error happened when attempting to close the tab:

ModeHandler: error handling key=, err=TypeError: Cannot read property 'selections' of undefined

To Reproduce

Steps to reproduce the behavior:

1. I had opened a few README.md files.
2. I intuitively wanted to close some of the files by hitting Control-W, before I realized the shortcut is Control-F4
3. I could see a few errors, one per file, but it's not always the case. I think I was in the command mode.

Expected behavior

I'm not sure. Maybe it's by design? If that's the case, please close it.

Screenshots

Environment (please complete the following information):

Version: 1.30.2 (system setup)
Commit: 61122f88f0bf01e2ac16bdb9e1bc4571755f5bd8
Date: 2019-01-07T22:54:13.295Z
Electron: 2.0.12
Chrome: 61.0.3163.100
Node.js: 8.9.3
V8: 6.1.534.41
OS: Windows_NT x64 10.0.17134

Additional context

Related: GH-3332

[J-Fields]

Duplicate of #6139