panic on small terminal width

[extrawurst]

gitui closes with a panic when resizing the terminal to weird small width like below 15:

16:06:42 [ERROR] panic: PanicInfo { payload: Any, message: Some(Trying to access position outside the buffer: x=14, y=0, area=Rect { x: 0, y: 0, width: 14, height: 54 }), location: Location { file: "/Users/stephan/.cargo/registry/src/github.com-1ecc6299db9ec823/tui-0.9.4/src/buffer.rs", line: 245, col: 9 } }
trace:
   0: backtrace::backtrace::trace_unsynchronized
   1: backtrace::backtrace::trace
   2: backtrace::capture::Backtrace::create
   3: backtrace::capture::Backtrace::new
   4: gitui::set_panic_handlers::{{closure}}
   5: std::panicking::rust_panic_with_hook
   6: _rust_begin_unwind
   7: std::panicking::begin_panic_fmt
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd/src/libstd/panicking.rs:332
   8: tui::buffer::Buffer::index_of
   9: tui::buffer::Buffer::set_stringn
  10: tui::buffer::Buffer::set_string
  11: <tui::widgets::tabs::Tabs<T> as tui::widgets::Widget>::render
  12: tui::terminal::Frame<B>::render_widget
  13: gitui::app::App::draw_tabs
  14: gitui::app::App::draw
  15: gitui::draw::{{closure}}
  16: tui::terminal::Terminal<B>::draw
  17: gitui::draw
  18: gitui::main
  19: std::rt::lang_start::{{closure}}
  20: std::panicking::try::do_call
  21: ___rust_maybe_catch_panic
  22: std::rt::lang_start_internal
  23: std::rt::lang_start
  24: _main

[extrawurst]

fixed via fdbd87b