Fix NPE in SourceRangeVerifier (when debugging)

Some nodes may return null for structuralFeatures if those nodes are
usually not available at given AST/Preview level (eg
StringTemplateExpression.propertyDescriptors(apiLevel, previewEnabled).
So let's handle this possible null case more gracefully.

org.eclipse.jdt.core/dom/org/eclipse/jdt/internal/core/dom/SourceRangeVerifier.java

@@ -57,6 +57,9 @@ public boolean preVisit2(ASTNode node) {
 		ASTNode previous = null;
 
 		List properties = node.structuralPropertiesForType();
+		if (properties == null) { // happens for some nodes that aren't usually available at AST level
+			return false;
+		}
 		for (Object p : properties) {
 			StructuralPropertyDescriptor property = (StructuralPropertyDescriptor) p;
 			if (property.isChildProperty()) {