Prevent an error when voicemail box does not exist.

includes/install/scripts/app/voicemail/index.lua

@@ -219,6 +219,9 @@
 --leave a message
 	if (voicemail_action == "save") then
 
+		--valid voicemail
+			if (voicemail_uuid ~= nil) then
+
 				--save the recording
 					timeouts = 0;
 					play_greeting();
@@ -270,6 +273,10 @@
 					if (message_length > 2) then
 						send_email(voicemail_id, uuid);
 					end
+			else
+				--invalid voicemail
+					session:hangup();
+			end
 	end
 
 --close the database connection