Crash when hitting Ctrl-W at the beginning of the edit buffer

[pothos]

First of all, impressive work - great experience to use it so far!

I just hit a panic when I pressed Ctrl-W (I think) when editing a line from the front.

[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/bash_server.rs:26:33
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: SHIFT }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: SHIFT }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Right, modifiers: ALT }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Right, modifiers: ALT }
[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/bash_server.rs:26:33
[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/bash_server.rs:26:33
[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/bash_server.rs:26:33
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: BackTab, modifiers: SHIFT }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'byte index 18446744073709551615 is out of bounds of ` <(cat ho)`', /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/alloc/src/string.rs:1250:24
[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs:    0:     0x55e00df2c34e - backtrace::backtrace::libunwind::trace::ha92b05c3835a19b3
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.62/src/backtrace/libunwind.rs:93:5
                           backtrace::backtrace::trace_unsynchronized::h5bd46d966599ad53
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.62/src/backtrace/mod.rs:66:5
                           backtrace::backtrace::trace::hc0cd2fe75e0630e9
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.62/src/backtrace/mod.rs:53:14
                           backtrace::capture::Backtrace::create::hbe88d678c6254fcc
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.62/src/capture.rs:176:9
                           backtrace::capture::Backtrace::new::h55226a7eaa89bbb3
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.62/src/capture.rs:140:22
   1:     0x55e00def63aa - nsh::main::{{closure}}::hbdf33c6259b88669
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs:190:25
   2:     0x55e00dfa04d6 - std::panicking::rust_panic_with_hook::h32c44b1364c1c247
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/std/src/panicking.rs:628:17
   3:     0x55e00dfc1c78 - std::panicking::begin_panic_handler::{{closure}}::he2e5f48fb16982d1
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/std/src/panicking.rs:521:13
   4:     0x55e00dfc1bf6 - std::sys_common::backtrace::__rust_end_short_backtrace::haea54a33f9e18aba
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/std/src/sys_common/backtrace.rs:141:18
   5:     0x55e00dfc1bb2 - rust_begin_unwind
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/std/src/panicking.rs:517:5
   6:     0x55e00de5fcb0 - core::panicking::panic_fmt::h824e0febbdf5e655
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/core/src/panicking.rs:101:14
   7:     0x55e00de601ac - core::str::slice_error_fail::h416bbb3b8269e469
   8:     0x55e00decd3cc - nsh::mainloop::UserInput::remove_until_word_start::hcfc8b7422d12c885
                           nsh::mainloop::Mainloop::handle_key_event::hc2d9e41aad7e6c31
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs:383:17
   9:     0x55e00dec911f - nsh::mainloop::Mainloop::handle_event::h9da7cc13584b9546
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs:267:44
  10:     0x55e00dec591e - nsh::mainloop::Mainloop::run::h89f95d1cb82c50be
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs:161:29
  11:     0x55e00def3a50 - nsh::interactive_mode::hcbcb561b5dd1dbc9
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs:68:5
                           nsh::shell_main::hc8f90789de9f5633
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs:124:13
  12:     0x55e00def608d - nsh::main::hd9825816e817867a
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs:203:5
  13:     0x55e00de67953 - core::ops::function::FnOnce::call_once::h049cc098aa9d1397
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/core/src/ops/function.rs:227:5
                           std::sys_common::backtrace::__rust_begin_short_backtrace::hc50c39f301db3c0e
                               at /rustc/09c42c45858d5f3aedfa670698275303a3d19afa/library/std/src/sys_common/backtrace.rs:125:18
  14:     0x55e00df0fbf4 - main
  15:     0x7fd1f9401e4a - __libc_start_main
                               at ./csu/../csu/libc-start.c:314:16
  16:     0x55e00de6582a - _start
  17:                0x0 - <unknown>

[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/bash_server.rs:26:33
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[WARN	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs: unsupported key event: KeyEvent { code: Left, modifiers: CONTROL }
[ERROR	] /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/main.rs: panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/bash_server.rs:26:33

[nuta]

Thank you for reporting the bug. It seems nsh crashes in UserInput::remove_until_word_start(). I'll fix it when I have time.

panicked at 'byte index 18446744073709551615 is out of bounds of ` <(cat ho)`',
...
   8:     0x55e00decd3cc - nsh::mainloop::UserInput::remove_until_word_start::hcfc8b7422d12c885
                           nsh::mainloop::Mainloop::handle_key_event::hc2d9e41aad7e6c31
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs:383:17
   9:     0x55e00dec911f - nsh::mainloop::Mainloop::handle_event::h9da7cc13584b9546
                               at /home/kai/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/nsh-0.4.2/src/mainloop.rs:267:44