Crash when switch to fullscreen mode, with `delta` as custom pager on Windows.

[CoolDove]

Describe the bug

Lazygit crashes when press + to switch fullscreen mode. Only happens when I set a custom pager.
If I remove the custom pager setting in config.yml, it doesn't crash anymore.

To Reproduce

1. Install delta, set it as custom pager. In config.yml:

git:
    pagers:
      - pager: delta --dark --paging=never

2. Open lazygit in any repository.
3. Press l to move the cursor to Local branches panel.
4. Press + and + to switch to fullscreen mode.
5. Lazygit crashes.

Screenshots

Version info:

commit=aafe61082e7ed383d318fd40e48f85645e6afc7b, build date=2026-07-15T11:34:26Z, build source=binaryRelease, version=0.63.1, os=windows, arch=amd64, git version=2.42.0.windows.2

Terminal info:

wezterm 20250703-070941-c7f4b081

Stacktrace

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x18 pc=0x7ff73a9c14f8]

goroutine 2472 [running]:
bufio.(*Scanner).Scan(0xc0001c0080)
        /opt/hostedtoolcache/go/1.25.12/x64/src/bufio/scan.go:219 +0x818
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).newPtyTask.func1.(*ViewBufferManager).NewCmdTask.4.4()
        /home/runner/work/lazygit/lazygit/pkg/tasks/tasks.go:222 +0x9d
github.com/jesseduffield/lazygit/pkg/utils.Safe.func1()
        /home/runner/work/lazygit/lazygit/pkg/utils/utils.go:70 +0x13
github.com/jesseduffield/lazygit/pkg/utils.SafeWithError(0xc0000b8008?)
        /home/runner/work/lazygit/lazygit/pkg/utils/utils.go:81 +0x56
github.com/jesseduffield/lazygit/pkg/utils.Safe(0x0?)
        /home/runner/work/lazygit/lazygit/pkg/utils/utils.go:70 +0x29
created by github.com/jesseduffield/lazygit/pkg/gui.(*Gui).newPtyTask.func1.(*ViewBufferManager).NewCmdTask.4 in goroutine 2619
        /home/runner/work/lazygit/lazygit/pkg/tasks/tasks.go:220 +0x53b

[NickGaertner]

Same issue here on windows using lazygit 0.63.1 on Windows Terminal. The crash also occurs if I only set difftastic as a pager.

Stacktrace:

❯❯❯ lazygit
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x18 pc=0x7ff6f83314f8]

goroutine 295 [running]:
bufio.(*Scanner).Scan(0xc0000ba200)
        /opt/hostedtoolcache/go/1.25.12/x64/src/bufio/scan.go:219 +0x818
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).newPtyTask.func1.(*ViewBufferManager).NewCmdTask.4.4()
        /home/runner/work/lazygit/lazygit/pkg/tasks/tasks.go:222 +0x9d
github.com/jesseduffield/lazygit/pkg/utils.Safe.func1()
        /home/runner/work/lazygit/lazygit/pkg/utils/utils.go:70 +0x13
github.com/jesseduffield/lazygit/pkg/utils.SafeWithError(0xc0003b0008?)
        /home/runner/work/lazygit/lazygit/pkg/utils/utils.go:81 +0x56
github.com/jesseduffield/lazygit/pkg/utils.Safe(0xc0003b0008?)
        /home/runner/work/lazygit/lazygit/pkg/utils/utils.go:70 +0x29
created by github.com/jesseduffield/lazygit/pkg/gui.(*Gui).newPtyTask.func1.(*ViewBufferManager).NewCmdTask.4 in goroutine 246
        /home/runner/work/lazygit/lazygit/pkg/tasks/tasks.go:220 +0x53b

Version:

commit=aafe61082e7ed383d318fd40e48f85645e6afc7b, build date=2026-07-15T11:34:26Z, build source=binaryRelease, version=0.63.1, os=windows, arch=amd64, git version=2.55.0.windows.3

[stefanhaller]

Here's a fix: #5838. Unfortunately I can't make a v0.63.2 release with the fix, because it would conflict and I don't feel like resolving those conflicts. The next release will probably be on Aug 2, so hopefully you can live with the bug until then, or use a master build once this is merged.