Crash in widget.(*Entry).SelectedText

[secsys-go]

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

We used the Fuzz engine to modify some Test(TestEntry_OnCopy) data, and then the following crash appeared. Is this due to some simulated keyboard operation?

How to reproduce

The simplified test code is in Example code

Screenshots

Crash Log

panic: runtime error: slice bounds out of range [:-1] [recovered]
        panic: runtime error: slice bounds out of range [:-1]

goroutine 88 [running]:
testing.tRunner.func1.2({0x87e8c0, 0xc0000240f0})
        /home/zjx/.local/go/src/testing/testing.go:1211 +0x24e
testing.tRunner.func1()
        /home/zjx/.local/go/src/testing/testing.go:1214 +0x218
panic({0x87e8c0, 0xc0000240f0})
        /home/zjx/.local/go/src/runtime/panic.go:1038 +0x215
fyne.io/fyne/v2/widget.(*Entry).SelectedText(0xc00000c1e0)
        /home/zjx/workspace/gowork/src/purelib/crashConfirm/fyne/widget/entry.go:442 +0x218
fyne.io/fyne/v2/widget.(*Entry).copyToClipboard(0xc00044dac0, {0x973e58, 0xc0005c8aa0})
        /home/zjx/workspace/gowork/src/purelib/crashConfirm/fyne/widget/entry.go:770 +0x3f
fyne.io/fyne/v2/widget.(*Entry).registerShortcut.func2({0x970180, 0xc0005c8ab0})
        /home/zjx/workspace/gowork/src/purelib/crashConfirm/fyne/widget/entry.go:887 +0x45
fyne.io/fyne/v2.(*ShortcutHandler).TypedShortcut(0xc00000c228, {0x970180, 0xc0005c8ab0})
        /home/zjx/workspace/gowork/src/purelib/crashConfirm/fyne/shortcut.go:21 +0x77
fyne.io/fyne/v2/widget.(*Entry).TypedShortcut(...)
        /home/zjx/workspace/gowork/src/purelib/crashConfirm/fyne/widget/entry.go:750
fyne.io/fyne/v2/widget_test.TestEntry_OnCopy(0x0)
        /home/zjx/workspace/gowork/src/purelib/crashConfirm/fyne/widget/entry_test.go:467 +0x14d

Example code

//part of the Test Code
	e := widget.NewEntry()
	e.SetText("\n\n\n\n\n\n\n\n\n\n")
	typeKeys(e, fyne.KeyRight, fyne.KeyRight, keyShiftLeftDown, fyne.KeyRight, fyne.KeyRight, fyne.KeyRight)

	clipboard := test.NewClipboard()
	shortcut := &fyne.ShortcutCopy{Clipboard: clipboard}
	e.TypedShortcut(shortcut)

Fyne version

commit 638ae24 (HEAD -> master, origin/master, origin/HEAD)

Go compiler version

1.17.8

Operating system

Linux

Operating system version

OS: Linux r920 4.15.0-159-generic #167-Ubuntu

Additional Information

No response

[andydotxyz]

Fixed on develop ready for next release