[Bug]: Error when closing all open leafs

[mgmeyers]

Describe the bug

When I close all open markdown files, this error is thrown:

For the most part, this error doesn't cause any issues, but it will prevent Kanban boards from cleaning up after themselves if they are the last leaf to close.

Relevant errors (if available)

Uncaught (in promise) TypeError: Cannot read property 'path' of null
    at t.getFileCache (app.js:1)
    at _t.eval (eval at <anonymous> (app.js:1), <anonymous>:35:4930)
    at Generator.next (<anonymous>)
    at eval (eval at <anonymous> (app.js:1), <anonymous>:6:982)
    at new Promise (<anonymous>)
    at _ (eval at <anonymous> (app.js:1), <anonymous>:6:802)
    at eval (eval at <anonymous> (app.js:1), <anonymous>:35:4832)
    at t.e.tryTrigger (app.js:1)
    at t.e.trigger (app.js:1)
    at t.trigger (app.js:1)
t.getFileCache @ app.js:1
eval @ VM219:35
eval @ VM219:6
_ @ VM219:6
eval @ VM219:35
e.tryTrigger @ app.js:1
e.trigger @ app.js:1
t.trigger @ app.js:1
t.activeLeafEvents @ app.js:1
a @ app.js:1
setTimeout (async)
l @ app.js:1
t.setActiveLeaf @ app.js:1
t.onLayoutChange @ app.js:1
t.insertChild @ app.js:1
t.createLeafInParent @ app.js:1
t.onLayoutChange @ app.js:1
t.removeChild @ app.js:1
t.detach @ app.js:1
t.detach @ app.js:1
eval @ VM173:71
o @ VM173:23
(anonymous) @ app.js:1
(anonymous) @ app.js:1

Steps to reproduce

Open a single markdown file and close it so that the No file is open message appears.

Expected Behavior

No response

Addition context

No response

Language

No response

API Name

No response

Operating system

macOS

[phibr0]

Looks like the File-Open event on workspace may fire with a file of null. Will add a check for that later.