[code folding] java.lang.NullPointerException: Cannot invoke "javax.swing.text.AttributeSet.getAttribute(Object)"

### Apache NetBeans version

Apache NetBeans 14

### What happened

Started NetBeans and got a notification saying:
"A java.lang.NullPointerException exception has occurred.
Please report this at https://netbeans.apache.org/nb/report-issue,
including a copy of your messages.log file as an attachment.
The messages.log file is located in your C:\Users\***\AppData\Roaming\NetBeans\14\var\log folder."

```
java.lang.NullPointerException: Cannot invoke "javax.swing.text.AttributeSet.getAttribute(Object)" because "attr" is null
at org.netbeans.modules.editor.fold.ui.CodeFoldingSideBar.resolveBackColor(CodeFoldingSideBar.java:353)
at org.netbeans.modules.editor.fold.ui.CodeFoldingSideBar.updateColors(CodeFoldingSideBar.java:368)
at org.netbeans.modules.editor.fold.ui.CodeFoldingSideBar.access$200(CodeFoldingSideBar.java:99)
at org.netbeans.modules.editor.fold.ui.CodeFoldingSideBar$2.preferenceChange(CodeFoldingSideBar.java:231)
at org.netbeans.modules.editor.fold.ui.CodeFoldingSideBar.addNotify(CodeFoldingSideBar.java:287)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at org.netbeans.modules.editor.impl.CustomizableSideBar$WestSidebarHolder.addNotify(CustomizableSideBar.java:288)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/javax.swing.JComponent.addNotify(JComponent.java:4839)
at java.desktop/javax.swing.JRootPane.addNotify(JRootPane.java:729)
at java.desktop/java.awt.Container.addNotify(Container.java:2804)
at java.desktop/java.awt.Window.addNotify(Window.java:791)
at java.desktop/java.awt.Frame.addNotify(Frame.java:495)
at java.desktop/java.awt.Window.pack(Window.java:829)
at org.netbeans.modules.java.editor.JavaEditorWarmUpTask.run(JavaEditorWarmUpTask.java:269)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:771)
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.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:741)
at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:136)
[catch] 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
```

[messages.log](https://github.com/apache/netbeans/files/9283055/messages.log)
[messages1.log](https://github.com/apache/netbeans/files/9283057/messages1.log)
[messages2.log](https://github.com/apache/netbeans/files/9283059/messages2.log)

### How to reproduce

Just started NetBeans 14 after updating from 12.0 to 14 and after importing 12.0 definitions.

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

Win10 64bit

### JDK

OpenJDK17.0.2

### Apache NetBeans packaging

Apache NetBeans binary zip

### Anything else

_No response_

### Are you willing to submit a pull request?

No

### Code of Conduct

Yes

Start in org.netbeans.modules.editor.fold.ui.CodeFoldingSideBar, especially resolveBackColor at line 353 and the updateColors call shown in the stack trace. Reproduce startup on Windows with imported NetBeans 12 definitions, then verify that NetBeans 14 no longer reports this NullPointerException during code-folding sidebar initialization.

Written by the indexing model from the issue text.