panic wile using <C-a> <C-x> on mulitple lines

[lexeyOK]

Summary

hx will panic if you decrement 10 to 9 on long enough promt

Reproduction Steps

https://asciinema.org/a/dPcMiojvfzk5X1Kt6EFfFVvPw using hx binary
https://asciinema.org/a/pACZkuCee8fOc0k9pm9OyEE4W using cargo r
I tried this:

1. hx
2. y5p:1<CR>5Cisomething[0<ESC>h10<C-a><C-x> (make 6 lines, write something[0] on each, select 0 on each line, increment till 10, decrement)

I expected this to happen:
6 lines with something[9] writen in them
Instead, this happened:
paniced with

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Char index out of bounds: char index 80, 
Rope/RopeSlice char length 78', /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/ropey-1.5.1-alpha/src/slice.rs:360:41
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

and

thread 'main' panicked at 'assertion failed: char_idx <= slice.len_chars()', helix-core/src/graphemes.rs:85:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Helix log

only log related to recent openting

~/.cache/helix/helix.log

...
2023-01-09T15:33:41.605 helix_view::editor [ERROR] editor error: 1 unsaved buffer(s) remaining: ["[scratch]"]
2023-01-09T15:33:44.412 helix_view::editor [ERROR] editor error: no such command: '!q'
2023-01-09T15:41:28.895 helix_view::editor [ERROR] Failed to initialize the LSP for `source.toml` { cannot find binary path }
2023-01-09T16:07:40.995 helix_view::editor [ERROR] Failed to initialize the LSP for `source.toml` { cannot find binary path }
2023-01-09T16:08:12.714 helix_view::editor [ERROR] editor error: no such command: '!git'
2023-01-09T16:08:34.544 helix_view::editor [ERROR] Failed to initialize the LSP for `source.toml` { cannot find binary path }
2023-01-09T16:32:11.168 helix_view::editor [ERROR] editor error: 1 unsaved buffer(s) remaining: ["[scratch]"]
2023-01-09T16:32:13.299 helix_view::editor [ERROR] editor error: 1 unsaved buffer(s) remaining: ["[scratch]"]

Platform

Linux

Terminal Emulator

alacritty 0.11.0-dev

Helix Version

helix 22.12 (96ff64a)

[the-mikedavis]

Also see #2019

[the-mikedavis]

This was fixed by #4123