HMCL Crash: JFXButton.getScene() is null on Toolbar Click

What it looks like in the log

java.lang.NullPointerException: Cannot invoke "javafx.scene.Scene.getRoot()" because the return value of "com.jfoenix.controls.JFXButton.getScene()" i

How to fix it

1. Open HMCL, go to Settings, and update the launcher to version 3.7.0.302 or newer (or switch from the Development channel back to the Stable channel).
2. If clicking inside HMCL prevents you from updating, download the latest HMCL release directly from the official HMCL website or GitHub Releases page and replace your existing launcher executable.
3. As a temporary workaround, simply close the crash popup window when it appears, as HMCL continues running normally behind it.

Check your own log