Only print messages from exceptions which are non-null

Submitted by:	Patrick Beard <beard@netscape.com>


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@268030 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/Main.java

@@ -131,7 +131,10 @@ public class Main {
             System.exit(0);
         }
         catch(Throwable exc) {
-            System.err.println(exc.getMessage());
+            String message = exc.getMessage();
+            if (message != null) {
+                System.err.println(message);
+            }
             System.exit(1);
         }
     }