Prevent NPE in method CheckRemoteSensitivity

PR: 24440


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@275615 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/optional/net/FTP.java

@@ -561,6 +561,9 @@ public class FTP
             return listFiles(directory, true);
         }
         private void checkRemoteSensitivity(FTPFile[] array, String directory) {
+            if (array == null) {
+                return;
+            }
             boolean candidateFound = false;
             String target = null;
             for (int icounter = 0; icounter < array.length; icounter++) {