Alt enter hotkey duplicates error messages causing persistent red underlines

### Apache NetBeans version

Apache NetBeans 28 latest daily build

### What happened

Using alt + enter while netbeans is still analyzing the source code (right after a change) causes the error message to duplicate. When that issue is fixed with alt + enter, because the message was duplicated, the error message remains and the line still has a red underline.
https://github.com/user-attachments/assets/41b70a41-e83d-41d8-8128-3a6c4838cd5c

### Language / Project Type / NetBeans Component

Works with any java project

### How to reproduce

Write this line without importing Map or HashMap. `Map hashMap = new HashMap();` Use alt + enter to import and quickly press alt + enter again, the error message for the second import will be duplicated. Also works with other bugs like a missing semicolon.

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

No / Don't know

### Operating System

macOS Sequioa 15.2

### JDK

24.0.1

### Apache NetBeans packaging

Own source build

### Anything else

The bug is present both in Netbeans 26 binary zip and in own source build.

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

Yes

No source file or test is named. Reproduce in a Java project by triggering Alt+Enter twice during source analysis, then trace the error-message and red-underline handling in NetBeans; done means the duplicate diagnostic is removed and the underline clears after the import or syntax error is fixed.

Written by the indexing model from the issue text.