invalide java editor warn/hint: the assigned value is never used

### Apache NetBeans version

Apache NetBeans 30

### What happened

Editing java file, get `the assigned value is never used`. This is not accurate, should be no warning.

### Language / Project Type / NetBeans Component

_No response_

### How to reproduce

1. Edit the following `class Warn`

Observe the warning on the indicated line: `data = switch(o) {`

Note: it looks like the analysis is getting confused by the `throw`. Replace the throw, like with `"j"`, and the warning goes away.

```java
package com.raelity.play.warn;

public class Warn {
public void f()
{
String data = null;
Object o = g(null);
if (o != null) {
data = switch(o) { // warn: the assigned value is never used
case Integer _ -> "i";
default -> throw new IllegalArgumentException();
};
}
g(data);
}
Object g(Object o) {
return 1;
}
}
```

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

No / Don't know

### Operating System

Linux harmony 6.17.9-76061709-generic #202511241048~1764704751~22.04~b24b425 SMP PREEMPT_DYNAMIC Tue D x86_64 x86_64 x86_64 GNU/Linux

### JDK

openjdk version "26" 2026-03-17 OpenJDK Runtime Environment (build 26+35-2893) OpenJDK 64-Bit Server VM (build 26+35-2893, mixed mode, sharing)

### Apache NetBeans packaging

Apache NetBeans binary zip

### Anything else

_No response_

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

No

Reproduce the warning in the NetBeans Java editor using the `Warn` class and the `data = switch(o)` line in method `f`. Compare the diagnostic when the switch default arm throws with the version returning a string, then verify that the false “assigned value is never used” warning disappears without changing the program behavior.

Written by the indexing model from the issue text.