Description of problem:

When show keyboard layout with ibus-libpinyin ("Intelligent Pinyin")
for Chinese, the gkbd-keyboard-display is crashed.

Version-Release number of selected component (if applicable):
gnome-shell-3.38.3-1.fc33.x86_64

How reproducible:

Add Chinese input method "Intelligent Pinyin", switch to use
this input method, then click the Show Keyboard Layout menu,
gkbd-keyboard-display is crashed.

Steps to Reproduce:
1. Add "Intelligent Pinyin" input method in gnome-control-center
2. Switch to use this input method
3. Click Show Keyboard Layout menu

Actual results:

The following command is run:
$ gkbd-keyboard-display -l default
and it crashed.

Expected results:

The current keyboard layout like "us" is shown.

Additional info:

Some ibus input method doesn't specify the keyboard layout,
it always use the current keyboard layout;
and ibus will return "default" for the keyboard layout.

Then gkbd-keyboard-display will crash with the "default" layout.