ICE on long where clause: called `Option::unwrap()` on a `None` value

enum A where for<'trivial> < <dir_structure::FmtWrapper as ::dir_structure::A>::Wr as ::dir_structure::WriteToAsync >::Future: F {}

thread 'main' panicked at src/tools/rustfmt/src/items.rs:567:10:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0:        0x11c6b35e7 - std::backtrace::Backtrace::create::hb33e5bccf1c8a42c
   1:        0x11c6b3535 - std::backtrace::Backtrace::force_capture::h6817b64990f269a6
   2:        0x11a0b7087 - rustc_driver_impl[5f54b1231065e765]::install_ice_hook::{closure#1}
   3:        0x11c6b45d1 - std::panicking::panic_with_hook::h5baaace6059c0027
   4:        0x11c6b4265 - std::panicking::panic_handler::{{closure}}::hbb5e20960cdb020d
   5:        0x11c6ad2f9 - std::sys::backtrace::__rust_end_short_backtrace::h39dfa0cbf126ab68
   6:        0x11c68e504 - __rustc[6009a88cdb7ad064]::rust_begin_unwind
   7:        0x11faeca2f - core::panicking::panic_fmt::h0e052a9623d88f7f
   8:        0x11faeca04 - core::panicking::panic::hf5f4fff998303e67
   9:        0x11faebf28 - core::option::unwrap_failed::h6a56d2efcf7efc38
  10:        0x10cf9e5b2 - <rustfmt_nightly[2796b9045b543bcf]::visitor::FmtVisitor>::visit_enum
  11:        0x10cf92cc3 - <rustfmt_nightly[2796b9045b543bcf]::visitor::FmtVisitor>::visit_item
  12:        0x10cfdfe55 - <rustfmt_nightly[2796b9045b543bcf]::visitor::FmtVisitor>::visit_items_with_reordering
  13:        0x10cf97a22 - <rustfmt_nightly[2796b9045b543bcf]::visitor::FmtVisitor>::walk_mod_items
  14:        0x10cf984b0 - <rustfmt_nightly[2796b9045b543bcf]::visitor::FmtVisitor>::format_separate_mod
  15:        0x10cf139cb - <rustfmt_nightly[2796b9045b543bcf]::Session<std[13294c1bc5dae938]::io::stdio::Stdout>>::format_input_inner::{closure#0}
  16:        0x10cf05169 - rustfmt[5c633625723718c7]::format_and_emit_report::<std[13294c1bc5dae938]::io::stdio::Stdout>
  17:        0x10cf19c91 - rustfmt[5c633625723718c7]::execute
  18:        0x10cf15a8c - rustfmt[5c633625723718c7]::main
  19:        0x10cf10886 - std[13294c1bc5dae938]::sys::backtrace::__rust_begin_short_backtrace::<fn(), ()>
  20:        0x10cf10cfc - std[13294c1bc5dae938]::rt::lang_start::<()>::{closure#0}
  21:        0x11c69d875 - std::rt::lang_start_internal::hee0eb4f99fe324f2
  22:        0x10cf254ef - _main
  23:     0x7ff808285418 - <unknown>


rustc version: 1.91.0-nightly (46c219bd2 2025-08-22)
platform: x86_64-apple-darwin

Reproduce the ICE by formatting the Rust snippet with rustfmt, then inspect src/tools/rustfmt/src/items.rs at line 567 and the visit_enum path shown in the backtrace. Done means the input no longer panics and is formatted or reported without an internal compiler error.