Corrected unexpected empty string in ChatEvent.formatEndPoint

src/main/java/fr/ill/ics/bridge/events/ChatEvent.java

@@ -91,7 +91,10 @@ public class ChatEvent {
 	
 	public static String formatEndPoint(String endPoint) {
 		String formattedEndPoint = endPoint.replace("tcp://", "");
-		formattedEndPoint = formattedEndPoint.substring(0, formattedEndPoint.indexOf(":"));
+		int index = formattedEndPoint.indexOf(":");
+		if (index != -1) {
+			formattedEndPoint = formattedEndPoint.substring(0, index);
+		}
 		return formattedEndPoint;
 	}