test-tool: Avoid crashes due to NULL-pointer dereferences

Avoid that certain test failures cause the test tool to trigger a
segmentation fault.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>

test-tool/test_extendedcopy_descr_limits.c

@@ -69,6 +69,10 @@ test_extendedcopy_descr_limits(void)
         RECEIVE_COPY_RESULTS(&edl_task, sd, SCSI_COPY_RESULTS_OP_PARAMS, 0,
                              (void **)&opp, EXPECT_STATUS_GOOD);
 
+        CU_ASSERT_NOT_EQUAL(opp, NULL);
+        if (!opp)
+                return;
+
         /* Allocate buffer to accommodate (MAX+1) target and
          * segment descriptors */
         alloc_len = XCOPY_DESC_OFFSET +