java.lang.NullPointerException: peer

### Apache NetBeans version

Apache NetBeans 25

### What happened

```
java.lang.NullPointerException: peer
at java.desktop/sun.awt.windows.WInputMethod.openCandidateWindow(Native Method)
at java.desktop/sun.awt.windows.WInputMethod$1.run(WInputMethod.java:627)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:98)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:747)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:744)
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)
```

### Language / Project Type / NetBeans Component

Java maven project

### How to reproduce

I don't know, happened in the background

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

No / Don't know

### Operating System

Windows

### JDK

JDK 8 compile, JDK 21 to run netbeans

### Apache NetBeans packaging

Apache NetBeans provided installer

### Anything else

_No response_

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

No

Start with the WInputMethod.openCandidateWindow stack trace and the NetBeans entry point at org.netbeans.core.TimableEventQueue.dispatchEvent. Investigate the background occurrence on Windows with JDK 21 running Apache NetBeans 25, then determine whether the issue can be reproduced and whether a NetBeans-side fix is possible. Done means documenting the cause and validating that the exception no longer occurs.

Written by the indexing model from the issue text.