GH-4968: server-spring - Close query result on pre-render exception

- Previously between getting the query response and rendering it
  to the desired output an exception could occur (e.g. due to unsupported
  result format) which would leave the result un-closed. This in turn
  would sometimes trigger an exception on closing the associated
  repo connection.

Author: vtermanis

tools/server-spring/src/main/java/org/eclipse/rdf4j/http/server/repository/handler/AbstractQueryRequestHandler.java

@@ -58,6 +58,7 @@ public ModelAndView handleQueryRequest(HttpServletRequest request, RequestMethod
 			HttpServletResponse response) throws HTTPException, IOException {
 
 		RepositoryConnection repositoryCon = null;
+		Object queryResponse = null;
 
 		try {
 			Repository repository = repositoryResolver.getRepository(request);
@@ -75,9 +76,6 @@ public ModelAndView handleQueryRequest(HttpServletRequest request, RequestMethod
 			boolean distinct = isDistinct(request);
 
 			try {
-
-				Object queryResponse;
-
 				if (headersOnly) {
 					queryResponse = null;
 				} else {
@@ -114,10 +112,22 @@ public ModelAndView handleQueryRequest(HttpServletRequest request, RequestMethod
 			}
 
 		} catch (Exception e) {
-			// only close the connection when an exception occurs. Otherwise, the QueryResultView will take care of
-			// closing it.
-			if (repositoryCon != null) {
-				repositoryCon.close();
+			// only close the response & connection when an exception occurs. Otherwise, the QueryResultView will take
+			// care of closing it.
+			try {
+				if (queryResponse instanceof AutoCloseable) {
+					((AutoCloseable) queryResponse).close();
+				}
+			} catch (Exception qre) {
+				logger.warn("Query response closing error", qre);
+			} finally {
+				try {
+					if (repositoryCon != null) {
+						repositoryCon.close();
+					}
+				} catch (Exception qre) {
+					logger.warn("Connection closing error", qre);
+				}
 			}
 			throw e;
 		}