refined fix so that XStreamMarshaller does not wrap IllegalArgumentException

Issue: SPR-9536

spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java

@@ -473,7 +473,6 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 
 	@Override
 	protected Object unmarshalDomNode(Node node) throws XmlMappingException {
-		try {
 		HierarchicalStreamReader streamReader;
 		if (node instanceof Document) {
 			streamReader = new DomReader((Document) node);
@@ -484,6 +483,7 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 		else {
 			throw new IllegalArgumentException("DOMSource contains neither Document nor Element");
 		}
+		try {
 			return getXStream().unmarshal(streamReader);
 		}
 		catch (Exception ex) {
@@ -523,8 +523,8 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 	protected Object unmarshalReader(Reader reader) throws XmlMappingException, IOException {
 		try {
 			HierarchicalStreamReader streamReader;
-			if (streamDriver != null) {
-				streamReader = streamDriver.createReader(reader);
+			if (this.streamDriver != null) {
+				streamReader = this.streamDriver.createReader(reader);
 			}
 			else {
 				streamReader = new XppReader(reader);