nil pointer dereference in dialog.Resize() for color picker

[ole108]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

A nil pointer dereference occurs when resizing a color picker dialog.
This only seems to only happen without setting an initial color with colorPicker.SetColor(c).
The real nil pointer occurs in popup.go.

It can be worked around with calling colorPicker.Refresh() before resizing.

How to reproduce

1. Create a color picker dialog (cp).
2. Do not set the initial color with cp.SetColor().
3. Call cp.Resize()
4. Call cp.Show()

Do the steps 1. to 4. again but with the second step modified to:
2. Do set set the initial color with cp.SetColor().

The third step (Resize) will crash the app.

Screenshots

No response

Example code

package main

import (
	"fmt"
	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/dialog"
	"image/color"
	"os"
)

func main() {
	fapp := app.NewWithID("app-with-unique-id")
	win := fapp.NewWindow("pick color")
	win.Resize(fyne.NewSize(500, 500))

	cp := dialog.NewColorPicker("", "", func(c color.Color) {
		fmt.Println("Color callback called!")
		win.Close()
		fapp.Quit()
	}, win)
	if len(os.Args) >= 2 && os.Args[1] == "1" {
		cp.Advanced = true
		cp.SetColor(color.White)
	}
	if len(os.Args) >= 3 && os.Args[2] == "2" {
		cp.Refresh() // update the picker internal UI
	}
	cp.Resize(fyne.NewSize(500, 500)) // this might crash!!!

	cp.Show()
	win.Show()
	fapp.Run()
}

Fyne version

2.5.2

Go compiler version

1.23.1

Operating system and version

Linux 6.1.0-26-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.112-1 (2024-09-30) x86_64 GNU/Linux

Additional Information

The fix is rather simple.
Just call p.updateUI() in an own Resize method for the color picker before calling the base dialogs Resize method.
That will fill p.win and so prevent win from being nil.

I would be happy to provide a pull request.