exp/textinput: a compositing text doesn't become empty

[hajimehoshi]

Ebitengine Version

1cc1e6e

Operating System

• Windows
• macOS
• Linux
• FreeBSD
• OpenBSD
• Android
• iOS
• Nintendo Switch
• PlayStation 5
• Xbox
• Web Browsers

Go Version (go version)

go version go1.26.0 windows/amd64

What steps will reproduce the problem?

1. Run exp/textinput
2. Press key 'A' to input 'あ' with a Japanese input (without comitting)
3. Press backspace

What is the expected result?

The text is removed

What happens instead?

'あ' remains

Anything else you feel useful to add?

No response