Replace fail() with assertThrows() in TreeItem test

[ptziegler]

This replaces the following pattern:

try {
	...
	fail();
} catch (IllegalArgumentException e) {
}

with

assertThrows(IllegalArgumentException.class, () -> ...);

[eclipse-platform-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

tests/org.eclipse.swt.tests/META-INF/MANIFEST.MF
tests/org.eclipse.swt.tests/pom.xml

An additional commit containing all the necessary changes was pushed to the top of this PR's branch. To obtain these changes (for example if you want to push more changes) either fetch from your fork or apply the git patch.

Git patch

From 6b4269dd513ccb6ac0a74c672dd192dbba5a423b Mon Sep 17 00:00:00 2001
From: Eclipse Platform Bot <[email protected]>
Date: Mon, 1 Dec 2025 17:07:11 +0000
Subject: [PATCH] Version bump(s) for 4.39 stream


diff --git a/tests/org.eclipse.swt.tests/META-INF/MANIFEST.MF b/tests/org.eclipse.swt.tests/META-INF/MANIFEST.MF
index 9f1d3b1108..4b571c7fe2 100644
--- a/tests/org.eclipse.swt.tests/META-INF/MANIFEST.MF
+++ b/tests/org.eclipse.swt.tests/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: Eclipse SWT Tests
 Bundle-SymbolicName: org.eclipse.swt.tests
-Bundle-Version: 3.107.1000.qualifier
+Bundle-Version: 3.107.1100.qualifier
 Bundle-Vendor: Eclipse.org
 Export-Package: org.eclipse.swt.tests.junit,
  org.eclipse.swt.tests.junit.performance
diff --git a/tests/org.eclipse.swt.tests/pom.xml b/tests/org.eclipse.swt.tests/pom.xml
index 18ae2d2c43..1675fabcb9 100644
--- a/tests/org.eclipse.swt.tests/pom.xml
+++ b/tests/org.eclipse.swt.tests/pom.xml
@@ -20,7 +20,7 @@
     <relativePath>../../local-build/local-build-parent/</relativePath>
   </parent>
   <artifactId>org.eclipse.swt.tests</artifactId>
-  <version>3.107.1000-SNAPSHOT</version>
+  <version>3.107.1100-SNAPSHOT</version>
   <packaging>eclipse-test-plugin</packaging>
   <properties>
     <tycho.testArgLine></tycho.testArgLine>
-- 
2.51.2

Further information are available in Common Build Issues - Missing version increments.

[github-actions]

Test Results

  118 files  ±0    118 suites  ±0   18m 6s ⏱️ + 1m 1s
4 653 tests ±0  4 635 ✅ ±0  18 💤 ±0  0 ❌ ±0 
  338 runs  ±0    334 ✅ ±0   4 💤 ±0  0 ❌ ±0 

Results for commit 2f34628. ± Comparison against base commit 941ff78.