Using JS template literals breaks qmlls' auto-completion list

Code

import QtQuick

Window {
    width: 800
    height: 600
    visible: true
    title: ` `


}

Steps to reproduce

1. At the end of the Window block, type in "Component." and inspect the auto-completion list
2. Undo your changes
3. Comment out title: ` ` (or replace the backticks ` with double-quotes ")
4. Repeat Step #1

Expected Outcomes (Step 4)
Without backticks, we get a sensible list for Component:

Actual Outcomes (Step 1)
With backticks, we get a list that is unrelated to Component:

Notes
The customer reported this on macOS, and I could reproduce it on macOS. However, I can't reproduce it on Windows.

I notice that QMLLS' auto-completion is very fast on macOS, but very slow on Windows. Could it be a race condition of some kind?