Click into empty area selects non-existent items, crashes on subsequent execute()

[Korkman]

Version: 0.8.1

Start with a short list, then click into the area above / below items. Note the right hand index does change to an invalid item number. Any execute() bind then crashes skim.

Edit: also happens using pgDn key: select last valid entry, press pgDn - the index is set beyond the valid range. Off by one in this case (set to index 24, for 24 items, but index starts at zero).

Example:
echo -e "1\n2\n3" | sk --bind 'enter:execute(echo ping)'

Trace:

thread 'main' panicked at 'model:act_output: failed to get item 27', src/selection.rs:268:36
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:77
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1052
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1426
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:472
  11: rust_begin_unwind
             at src/libstd/panicking.rs:380
  12: std::panicking::begin_panic_fmt
             at src/libstd/panicking.rs:334
  13: skim::selection::Selection::get_selected_wrapped_items::{{closure}}
  14: skim::selection::Selection::get_selected_wrapped_items
  15: skim::model::Model::act_execute_silent
  16: skim::model::Model::start
  17: skim::Skim::run_with
  18: sk::real_main
  19: sk::main
  20: std::rt::lang_start::{{closure}}
  21: main
  22: __libc_start_main
  23: _start