ebiten: calling ScreenSizeInFullscreen panics on browsers

[tinne26]

Ebitengine Version

v2.7.2

Operating System

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

Go Version (go version)

go1.22.2

What steps will reproduce the problem?

Compiling and executing the following program on the browser (e.g. $env:GOOS="js"; $env:GOARCH="wasm"; go build -o exec.wasm main.go):

package main

import "github.com/hajimehoshi/ebiten/v2"

type Game struct {}
func (*Game) Layout(w, h int) (int, int) { return w, h }
func (*Game) Update() error { return nil }
func (*Game) Draw(*ebiten.Image) {}

func main() {
	w, h := ebiten.ScreenSizeInFullscreen()
	_, _ = w, h
	err := ebiten.RunGame(&Game{})
	if err != nil { panic(err) }
}

I also tried with runtime.LockOSThread(), go1.18.10, both Firefox and Chrome, etc.; everything panics. Using Monitor().Size() works, though.

Sample Firefox error output:

panic: syscall/js: call of Value.Int on undefined
<empty string>
goroutine 1 [running]:
syscall/js.Value.float({{}, 0x0, 0x0}, {0x82666, 0x9})
	syscall/js/js.go:454 +0x10
syscall/js.Value.Int(...)
	syscall/js/js.go:471
github.com/hajimehoshi/ebiten/v2/internal/ui.(*UserInterface).ScreenSizeInFullscreen(0x19bc008)
	github.com/hajimehoshi/ebiten/v2@v2.7.2/internal/ui/screensizeinfullscreen_js.go:19 +0x5
github.com/hajimehoshi/ebiten/v2.ScreenSizeInFullscreen(...)
	github.com/hajimehoshi/ebiten/v2@v2.7.2/run.go:358
main.main()
	./main.go:14 +0x6

What is the expected result?

No panic.

What happens instead?

Panic.

Anything else you feel useful to add?

No response

[hajimehoshi]

What about Chrome?

[hajimehoshi]

I could reproduce this even on macOS / Firefox and Chrome.

[hajimehoshi]

This worked with v2.6, so this is a regression.