OSMUX_Emulation: Add special error case for port events

This way it's easier to quickly spot there was a problem with the socket
connection.

Change-Id: I962bf4837a9e359576c42a51a9919891186c7100
diff --git a/library/OSMUX_Emulation.ttcn b/library/OSMUX_Emulation.ttcn
index 5d9a95e..6189266 100644
--- a/library/OSMUX_Emulation.ttcn
+++ b/library/OSMUX_Emulation.ttcn
@@ -422,7 +422,7 @@
 	var OsmuxRxHandle rx_hdl;
 	var OsmuxTxHandle tx_hdl;
 	var octetstring payload_truncated;
-
+	var PortEvent port_event;
 	timer T_transmit := int2float(g_cfg.tx_duration_ms)/1000.0;
 	var Osmux_RecvFrom rx_osmux;
 	var PDU_Osmux_AMR  rx_amr;
@@ -569,6 +569,11 @@
 			T_transmit.start;
 		}
 
+		[] OSMUX.receive(PortEvent:?) -> value port_event {
+			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
+						log2str("Received unexpected port event from Osmux:", port_event));
+		}
+
 		/* fail on any unexpected messages */
 		[] OSMUX.receive {
 			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,