ggsn: Avoid dynamic test case error

During TC_addr_pool_exhaustion, if all of the pdp context activations
were unsuccessful, teic_list is an empty list. We therefore cannot
unconditionally obtain its first element.

This patch avoids the related "Index overflow in a value of type
@PreGenRecordOf.PREGEN_RECORD_OF_OCTETSTRING: The index is 0, but the
value has only 0 elements."

Related: OS#6423
Change-Id: I7c7a84ed8343fb48e841248f86d37972f4674ed0
diff --git a/ggsn_tests/GGSN_Tests.ttcn b/ggsn_tests/GGSN_Tests.ttcn
index e2d5fb2..8672947 100644
--- a/ggsn_tests/GGSN_Tests.ttcn
+++ b/ggsn_tests/GGSN_Tests.ttcn
@@ -2080,7 +2080,7 @@
 		[Gx_PROC.checkstate("Connected")] as_DIA_Gx_CCR(TERMINATION_REQUEST) { repeat; }
 		[Gy_PROC.checkstate("Connected")] as_DIA_Gy_CCR(omit, TERMINATION_REQUEST) { repeat; }
 		[] pingpong();
-		[] T_next.timeout {
+		[lengthof(teic_list) > 0] T_next.timeout {
 			f_send_gtpc(ts_GTPC_DeletePDP(g_peer_c, g_c_seq_nr, teic_list[next_req_ctx], '0001'B, '1'B));
 			next_req_ctx := next_req_ctx + 1;
 			if (next_req_ctx < num_ctx) {