Linux - NullPointerException Cannot read field "next" -- happens when I close the GUI

What I did:

1: Run custom project.

2: Build process is running

3: Click Pause button

4: Ensure CPU load become under 5%

5: Click Stop button

6: Click [X] button on right, top of the GUI

7: Crash log is generated.

System:

StrategyQuant X Pro build 135

OS:

Ubuntu 21.10

Log:

03:03:28.691 [Thread-49976] INFO  c.s.t.project.ProgressEngine - Build strategies : Databank 'USDJPY H1 v3 - Build' synchronized to files - 1 records updated in 0.02 s.
05:03:28.716 [Thread-49976] INFO  c.s.t.project.ProgressEngine - Build strategies : Databank 'USDJPY H1 v3 - Build' synchronized to files - 1 records updated in 0.03 s.
06:03:28.922 [Thread-49976] INFO  c.s.t.project.ProgressEngine - Build strategies : Databank 'USDJPY H1 v3 - Build' synchronized to files - 8 records updated in 0.21 s.
07:03:28.942 [Thread-49976] INFO  c.s.t.project.ProgressEngine - Build strategies : Databank 'USDJPY H1 v3 - Build' synchronized to files - 1 records updated in 0.02 s.
09:03:29.004 [Thread-49976] INFO  c.s.t.project.ProgressEngine - Build strategies : Databank 'USDJPY H1 v3 - Build' synchronized to files - 3 records updated in 0.06 s.
10:03:29.025 [Thread-49976] INFO  c.s.t.project.ProgressEngine - Build strategies : Databank 'USDJPY H1 v3 - Build' synchronized to files - 1 records updated in 0.02 s.
11:21:15.803 [qtp1681629677-590] INFO  c.s.t.project.ProgressEngine - Build strategies : Project paused
11:22:57.337 [qtp1681629677-598] INFO  c.s.t.project.ProgressEngine - Build strategies : Project stopped
11:22:57.403 [Thread-12653] INFO  c.s.t.project.ProgressEngine - Project finished
11:22:57.440 [Nonblocking computeThread - 0 - Builder_0] INFO  c.s.t.project.ProgressEngine - Finished in 18h 19m
11:23:00.773 [AWT-EventQueue-0] INFO  c.strategyquant.webguilib.BrowserGUI - Exit 1
11:23:10.047 [AWT-EventQueue-0] INFO  c.strategyquant.webguilib.BrowserGUI - Exit application
11:23:11.098 [AWT-EventQueue-0] INFO  o.e.jetty.server.AbstractConnector - Stopped ServerConnector@7fbf26fc{HTTP/1.1,[http/1.1]}{0.0.0.0:8080}
11:23:11.098 [AWT-EventQueue-0] INFO  org.eclipse.jetty.server.session - node0 Stopped scavenging
11:23:11.108 [AWT-EventQueue-0] ERROR c.strategyquant.strategyquant.SQApp - Error while closing grid engine
java.lang.NullPointerException: Cannot read field "next" because "this.next" is null
    at java.base/java.util.LinkedList$ListItr.next(LinkedList.java:897) ~[na:na]
    at com.strategyquant.gridlib.concurrent.ThreadPool.close(Unknown Source) ~[SQGridLib2.jar:na]
    at com.strategyquant.gridlib.compute.performer.MultithreadComputePerformer.close(Unknown Source) ~[SQGridLib2.jar:na]
    at com.strategyquant.gridlib.client.Compute.close(Unknown Source) ~[SQGridLib2.jar:na]
    at com.strategyquant.gridlib.client.GridClient.close(Unknown Source) ~[SQGridLib2.jar:na]
    at com.strategyquant.strategyquant.SQApp.exitApp(Unknown Source) ~[na:na]
    at com.strategyquant.lib.app.MainApp.exitApp(Unknown Source) ~[na:na]
    at com.strategyquant.webguilib.BrowserGUI.exit(Unknown Source) ~[SQWebGUILib.jar:na]
    at com.strategyquant.webguilib.BrowserGUI.exitProgram(Unknown Source) ~[SQWebGUILib.jar:na]
    at com.strategyquant.webguilib.BrowserGUI$1.windowClosing(Unknown Source) ~[SQWebGUILib.jar:na]
    at java.desktop/java.awt.AWTEventMulticaster.windowClosing(AWTEventMulticaster.java:357) ~[na:na]
    at java.desktop/java.awt.AWTEventMulticaster.windowClosing(AWTEventMulticaster.java:357) ~[na:na]
    at java.desktop/java.awt.AWTEventMulticaster.windowClosing(AWTEventMulticaster.java:357) ~[na:na]
    at java.desktop/java.awt.Window.processWindowEvent(Window.java:2075) ~[na:na]
    at java.desktop/javax.swing.JFrame.processWindowEvent(JFrame.java:298) ~[na:na]
    at java.desktop/java.awt.Window.processEvent(Window.java:2034) ~[na:na]
    at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4990) ~[na:na]
    at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321) ~[na:na]
    at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2769) ~[na:na]
    at java.desktop/java.awt.Component.dispatchEvent(Component.java:4822) ~[na:na]
    at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772) ~[na:na]
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721) ~[na:na]
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715) ~[na:na]
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:391) ~[na:na]
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85) ~[na:na]
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95) ~[na:na]
    at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745) ~[na:na]
    at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743) ~[na:na]
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:391) ~[na:na]
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85) ~[na:na]
    at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742) ~[na:na]
    at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203) ~[na:na]
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124) ~[na:na]
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113) ~[na:na]
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109) ~[na:na]
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) ~[na:na]
    at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90) ~[na:na]
11:23:12.015 [Thread-65] ERROR c.strategyquant.webguilib.BrowserGUI - SQ app websockets not connected 0 times in a row
11:23:14.110 [Timer-147] INFO  com.strategyquant.lib.app.MainApp - Exit app.