NullPointerException related to hover listener

[jfree]

When I run FirePlaceMain and view the Allocations flame graph I observe the following NullPointerException:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke "io.github.bric3.fireplace.flamegraph.FlameGraph$HoveringListener.onFrameHover(io.github.bric3.fireplace.flamegraph.FrameBox, java.awt.Rectangle, java.awt.event.MouseEvent)" because "this.hoveringListener" is null
	at io.github.bric3.fireplace.flamegraph.FlameGraph$FlameGraphMouseInputListener.mouseMoved(FlameGraph.java:471)
	at java.desktop/java.awt.Component.processMouseMotionEvent(Component.java:6671)
	at java.desktop/javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3407)
	at java.desktop/java.awt.Component.processEvent(Component.java:6395)
	at java.desktop/java.awt.Container.processEvent(Container.java:2266)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5001)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
	at io.github.bric3.fireplace.core.ui.MouseInputListenerWorkaroundForToolTipEnabledComponent.dispatch(MouseInputListenerWorkaroundForToolTipEnabledComponent.java:57)
	at io.github.bric3.fireplace.core.ui.MouseInputListenerWorkaroundForToolTipEnabledComponent.mouseMoved(MouseInputListenerWorkaroundForToolTipEnabledComponent.java:99)
	at java.desktop/java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:337)
	at java.desktop/java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:337)
	at java.desktop/java.awt.Component.processMouseMotionEvent(Component.java:6671)
	at java.desktop/javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3407)
	at java.desktop/java.awt.Component.processEvent(Component.java:6395)
	at java.desktop/java.awt.Container.processEvent(Container.java:2266)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5001)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4948)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4588)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4516)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2310)
	at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:746)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:744)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:743)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

The fix is simple, PR is coming.