assertion 'gtk_accel_group_from_accel_closure (accel_closure) != NULL' failed

I'm seeing following error message on stdout when starting pluma (Arch Linux x86_64):

```
(pluma:1066316): Gtk-CRITICAL **: 18:36:24.676: gtk_accel_label_set_accel_closure: assertion 'gtk_accel_group_from_accel_closure (accel_closure) != NULL' failed
```

```
$ pluma --version    
pluma - Version 1.28.0
```