Command block text field isn't focused when opening the GUI anymore

The bug

In previous versions (19w14a and below), you could open up a command block and immediately begin typing the command, as the input box was selected and had the cursor inside. This broke in 19w14b, and you have to click the box before you can start typing.

How to reproduce

1. Place and open a command block
2. Start typing immediately
   →  Nothing happens, box isn't focused