Failed to handle key=<Esc>. Cannot read property 'cursorStartPosition' of undefined

Problem: loses the ability to accept the key.

Environment

• MacOS 10.15.7. Macbook Pro, 15", 2019
• VSCode 1.15.1 with Vim extension.

To Reproduce

1. Open VS Code for an existing script.
2. Type control-v at the start of a line.
3. Hit j a bunch of times to multi-select the first character of several rows
4. Hit capital I to go to multi-insert mode
5. Type # then <space> to enter those characters, then <Esc> to make them appear on each line

• Note: there was a two-space indent for some, but not all of these lines.

6. Type u to undo because that's the wrong comment character for typescript
7. Notice that the first characters of those rows are now selected again.
8. Type /

Expected result: I input a / character

Actual result:

VSCode complains when I enter any character at this point.

VSCodeVim version: 1.17.1

TypeError: Failed to handle key=<Esc>. Cannot read property 'cursorStartPosition' of undefined
	at A.exec (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:9:437666)
	at A.execCount (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:1:37019)
	at F.runAction (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:9:475409)
	at F.handleKeyAsAnAction (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:9:474805)
	at F.handleKeyEvent (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:9:471614)
	at runMicrotasks (<anonymous>)
	at processTicksAndRejections (internal/process/task_queues.js:94:5)
	at async Object.promise (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:9:231560)
	at async Object.runTasks (/Users/will/.vscode/extensions/vscodevim.vim-1.17.1/out/extension.js:9:621914)

Reproduce the multi-selection, insert, undo, and slash sequence in VS Code using the stated macOS and extension versions. Start from the key-handling path shown in the extension.js stack trace, then verify that Escape and the following slash are accepted without an exception and that the expected selections remain intact.