return null from nextStringValue() at end of input

src/main/java/tools/jackson/dataformat/xml/deser/FromXmlParser.java

@@ -996,6 +996,7 @@ public String nextStringValue() throws JacksonException
             break;
         case XmlTokenStream.XML_END:
             _updateTokenToNull();
+            break;
         default:
             return _internalErrorUnknownToken(token);
         }

src/test/java/tools/jackson/dataformat/xml/stream/XmlParserNextXxxTest.java

@@ -7,6 +7,7 @@
 import tools.jackson.dataformat.xml.deser.FromXmlParser;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 public class XmlParserNextXxxTest extends XmlTestUtil
 {
@@ -43,4 +44,26 @@ public void testXmlAttributesWithNextTextValue() throws Exception
         assertToken(JsonToken.END_OBJECT, xp.nextToken()); // </data>
         xp.close();
     }
+
+    // nextStringValue() must honor the JsonParser contract at end of input:
+    // return null, same as nextToken() does, instead of leaking an unchecked
+    // IllegalStateException from the internal XML_END branch.
+    @Test
+    public void testNextStringValueAtEndOfInput() throws Exception
+    {
+        final String XML = "<data max=\"7\" offset=\"9\"/>";
+
+        JsonParser xp = xmlMapper(false).createParser(XML);
+
+        assertToken(JsonToken.START_OBJECT, xp.nextToken()); // <data>
+        assertToken(JsonToken.PROPERTY_NAME, xp.nextToken()); // max
+        assertEquals("7", xp.nextStringValue());
+        assertToken(JsonToken.PROPERTY_NAME, xp.nextToken()); // offset
+        assertEquals("9", xp.nextStringValue());
+        assertToken(JsonToken.END_OBJECT, xp.nextToken()); // </data>
+
+        // One more call past the end: should quietly report end-of-input
+        assertNull(xp.nextStringValue());
+        xp.close();
+    }
 }