Failed to handle key=a. Cannot read property 'getFocusElement' of null

To Reproduce
Steps to reproduce the behavior:

Include the following in settings.json:

    "vim.leader": "<space>",
    "vim.normalModeKeyBindings": [
        {
            "before": [
                "<leader>",
                "a"
            ],
            "commands": [
                "problems.action.showQuickFixes"
            ]
        }
    ]

Then go to a problem in the code. Attempt to do <space>a to bring up quickfix, and the given problem occurs. In the same position if you hit Ctr + period key, it brings up the quickfix menu.

VSCodeVim version: 1.18.9

TypeError: Cannot read property 'getFocusElement' of null
    at handler (file:///usr/share/vscodium-bin/resources/app/out/vs/workbench/workbench.desktop.main.js:2555:1426)
    at C.invokeFunction (file:///usr/share/vscodium-bin/resources/app/out/vs/workbench/workbench.desktop.main.js:614:20943)
    at C._tryExecuteCommand (file:///usr/share/vscodium-bin/resources/app/out/vs/workbench/workbench.desktop.main.js:1534:3492)
    at file:///usr/share/vscodium-bin/resources/app/out/vs/workbench/workbench.desktop.main.js:1534:3241

Start by reproducing the problem with the shown settings.json mapping for a and the problems.action.showQuickFixes command while a problem is selected. Compare that path with Ctrl+. and trace the keybinding command handling until the null getFocusElement call is identified; done means the mapping opens the quick-fix menu without the error.