return on error to prevent crash

rs232controller.c

@@ -609,6 +609,7 @@ static void encodeTerminator(char *result, char *terminator)
 
   if (terminator == NULL) {
     result[0] = '\0';
+    return;
   }
   len = strlen(terminator);
   snprintf(pBuffer,sizeof(pBuffer)-1, "0x%x", (int) terminator[0]);