Fix possible IndexOutOfBoundsException

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlTokenStream.java

@@ -557,7 +557,7 @@ private final String _collectUntilTag() throws XMLStreamException
         }
 
         CharSequence chars = null;
-        while (true) {
+        while (_xmlReader.hasNext()) {
             switch (_xmlReader.next()) {
             case XMLStreamConstants.START_ELEMENT:
                 return (chars == null) ? "" : chars.toString();