Handle swaybar status line errors

The event loop API was redesigned to avoid race conditions as well.
Fixes #1583

include/swaybar/status_line.h

@@ -48,6 +48,12 @@ struct status_line *init_status_line();
  */
 bool handle_status_line(struct bar *bar);
 
+/**
+ * This should be called if statusline input cannot be accessed.
+ * It will set an error statusline instead of using the status command
+ */
+void handle_status_hup(struct status_line *status);
+
 /**
  * Handle mouse clicks.
  */