[UWS] Fix JobInfo destruction when no file associated

src/uws/job/jobInfo/XMLJobInfo.java

@@ -16,7 +16,7 @@ package uws.job.jobInfo;
  * You should have received a copy of the GNU Lesser General Public License
  * along with UWSLibrary.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2017-2019 - Astronomisches Rechen Institut (ARI),
+ * Copyright 2017-2020 - Astronomisches Rechen Institut (ARI),
  *                       UDS/Centre de Données astronomiques de Strasbourg (CDS)
  */
 
@@ -142,7 +142,7 @@ import uws.service.request.UploadFile;
  * </p>
  *
  * @author Gr&eacute;gory Mantelet (ARI;CDS)
- * @version 4.4 (03/2019)
+ * @version 4.5 (05/2020)
  * @since 4.2
  */
 public class XMLJobInfo implements JobInfo {
@@ -323,12 +323,14 @@ public class XMLJobInfo implements JobInfo {
 
 	@Override
 	public void destroy() throws UWSException {
+		if (file != null) {
 			try {
 				file.deleteFile();
 			} catch(IOException ioe) {
 				throw new UWSException(UWSException.INTERNAL_SERVER_ERROR, ioe, "Error when deleting a JobInfo file!");
 			}
 		}
+	}
 
 	/**
 	 * Serialize this {@link XMLJobInfo}.