Crash on clicking tab

Not sure if this is a virtboard crash, but it's very likely confirmed.

Steps to reproduce:

1. Use wlroots from wlroots!40 (closed)
2. Start the calendar
3. Start yad --entry (keyboard pops up)
4. Type "tab" in virtboard (Observation 1)
5. Kill yad
6. Start yad --entry (Observation 2)

Expected result:

1. Focus moves to "OK", keyboard hides
2. Keyboard appears

Actual result:

1. Key gets stuck
2. Keyboard crashes