NPE in SmartTypingConfigurationBlock when no Java editor is active

The Typing preference page threw an NPE when opened with no active Java
editor, since a null compilation unit was dereferenced without a check;
this adds the missing null guard, consistent with the existing null-safe
handling right below it.

Fix: #3068

Author: subyssurendran666

org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/SmartTypingConfigurationBlock.java

@@ -232,7 +232,7 @@ private void addAutoclosingSection(Composite composite) {
 		createDependency(master, slave);
 
 		ICompilationUnit cu= getCompilationUnit();
-		IJavaProject project= cu.getJavaProject();
+		IJavaProject project= cu != null ? cu.getJavaProject() : null;
 		String compliance= project != null
 				? project.getOption(JavaCore.COMPILER_COMPLIANCE, true)
 				: JavaCore.getOption(JavaCore.COMPILER_COMPLIANCE);