Reproducible panic: ToggleHelp from CommandMode

Description of the problem or steps to reproduce

Create a binding to ToggleHelp from CommandMode, then do so.

❯ cat .config/micro/bindings.json
{
    "command": {
        "Ctrl-g": "ToggleHelp"
    }
}

❯ micro # enter CommandMode (Ctrl-e), then ToggleHelp (Ctrl-g)
Micro encountered an error: runtime.errorString runtime error: invalid memory address or nil pointer dereference
runtime/panic.go:221 (0x559729ee0347)
runtime/panic.go:220 (0x559729ee0317)
github.com/zyedidia/micro/v2/internal/views/splits.go:409 (0x55972a30c775)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:548 (0x55972a32fff9)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:559 (0x55972a33345a)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:559 (0x55972a333414)
github.com/zyedidia/micro/v2/internal/action/actions.go:1419 (0x55972a328bad)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:26 (0x55972a33afb6)
github.com/zyedidia/micro/v2/internal/action/infopane.go:137 (0x55972a33b952)
github.com/zyedidia/micro/v2/internal/action/infopane.go:93 (0x55972a33b4fe)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:443 (0x55972a36acb3)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:382 (0x55972a36a84a)
runtime/proc.go:255 (0x559729ecd0c7)
runtime/asm_amd64.s:1581 (0x559729efb581)
 
If you can reproduce this error, please report it at https://github.com/zyedidia/micro/issues

Specifications

Was able to reproduce for the latest binary release (v2.0.10) and latest commit (2f4675e):
Commit hash: b9763856, 2f4675e
OS: Linux (Arch)
Terminal: kitty

Was also able to reproduce the panic in a Windows 10 VM with the latest binary release.

Reproduce the panic by binding ToggleHelp in CommandMode, then start at internal/views/splits.go:409 and follow the calls through internal/action/bufpane.go:548-559 and actions.go:1419. Check the behavior on the reported Linux and Windows scenarios; done means ToggleHelp no longer panics when invoked from CommandMode.