GitUI panics in RemoteList with no remotes configured ("git: inconclusive remotes")

[Yi2255]

Describe the bug
GitUI exits with an error in a newly initialized repo when triggering pull-related action with ambiguous/incomplete remote setup.

Observed error:
Error: git: inconclusive remotes

To Reproduce
Steps to reproduce the behavior:

1. Create a clean repo:
   mkdir -p /i4/gitui_crash1
   cd /i4/gitui_crash1
   git init
2. Start GitUI:
   gitui
3. Press keys:
   2
   p
4. See error and exit/backtrace.
   panicked at /i4/gitui/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/gitui-0.28.0/src/popups/remotelist.rs:460:30:
   index out of bounds: the len is 0 but the index is 0

trace:
0: gitui::set_panic_handler::{{closure}}
1: std::panicking::panic_with_hook
2: std::panicking::panic_handler::{{closure}}
3: std::sys::backtrace::__rust_end_short_backtrace
4: __rustc::rust_begin_unwind
5: core::panicking::panic_fmt
6: core::panicking::panic_bounds_check
7: <alloc::vec::Vec<T,A> as core::ops::index::Index>::index
8: <gitui::popups::remotelist::RemoteListPopup as gitui::components::Component>::event
9: gitui::components::event_pump
10: gitui::run_app
11: gitui::main
12: std::sys::backtrace::__rust_begin_short_backtrace
13: main
14: __libc_start_call_main
at ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
15: __libc_start_main_impl
at ./csu/../csu/libc-start.c:360:3
16: _start