Widget.getData: fix NPE

[jukzi]

fix java.lang.NullPointerException: Cannot read the array length because "table" is null

As Widget.setData(Object) can be called with null argument even if KEYED_DATA is set.

[jukzi]

NPE logged during teardown in https://download.eclipse.org/eclipse/downloads/drops4/I20241008-1810/testresults/ep434I-unit-win32-java17_win32.win32.x86_64_17/org.eclipse.ui.tests.UiTestSuite.txt

!ENTRY org.eclipse.ui 4 0 2024-10-09 09:20:24.654
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.NullPointerException: Cannot read the array length because "table" is null
	at org.eclipse.swt.widgets.Widget.getData(Widget.java:598)
	at org.eclipse.e4.ui.css.swt.engine.AbstractCSSSWTEngineImpl.isStylable(AbstractCSSSWTEngineImpl.java:117)
	at org.eclipse.e4.ui.css.swt.engine.AbstractCSSSWTEngineImpl.getElement(AbstractCSSSWTEngineImpl.java:96)
	at org.eclipse.e4.ui.css.core.impl.engine.AbstractCSSEngine.applyStyles(AbstractCSSEngine.java:374)
	at org.eclipse.e4.ui.css.core.impl.engine.AbstractCSSEngine.applyStyles(AbstractCSSEngine.java:369)
	at org.eclipse.e4.ui.css.swt.engine.CSSSWTApplyStylesListener.lambda$0(CSSSWTApplyStylesListener.java:31)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4389)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4381)
	at org.eclipse.swt.widgets.Display.runSkin(Display.java:4265)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3767)
	at org.eclipse.ui.tests.harness.util.UITestCase.processEvents(UITestCase.java:245)
	at org.eclipse.ui.tests.harness.util.CloseTestWindowsRule.after(CloseTestWindowsRule.java:46)
	at org.eclipse.ui.tests.harness.util.UITestCase.doTearDown(UITestCase.java:239)
	at org.eclipse.ui.tests.harness.util.UITestCase.tearDown(UITestCase.java:214)

[github-actions]

Test Results

   486 files  ±0     486 suites  ±0   7m 43s ⏱️ -22s
 4 159 tests ±0   4 151 ✅ ±0   8 💤 ±0  0 ❌ ±0 
16 390 runs  ±0  16 298 ✅ ±0  92 💤 ±0  0 ❌ ±0 

Results for commit 3051a6e. ± Comparison against base commit bb0f8dd.

[jukzi]

ignoring random fail #1523