thread 'LspServer' panicked at crates\base-db\src\lib.rs:133:14:

Happened when switching revisions where one of the files I had open no longer exists

thread 'LspServer' panicked at crates\base-db\src\lib.rs:133:14:
Unable to fetch FileSourceRootInput; this is a bug
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library\std\src\panicking.rs:692
   1: core::panicking::panic_fmt
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library\core\src\panicking.rs:75
   2: core::panicking::panic_display
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library\core\src\panicking.rs:261
   3: core::option::expect_failed
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library\core\src\option.rs:2024
   4: <ide_db::RootDatabase as base_db::SourceDatabase>::file_source_root
   5: base_db::change::FileChange::apply
   6: hir_expand::change::ChangeWithProcMacros::apply
   7: ide_db::apply_change::<impl ide_db::RootDatabase>::apply_change
   8: rust_analyzer::global_state::GlobalState::new
   9: rust_analyzer::main_loop::<impl rust_analyzer::global_state::GlobalState>::run
  10: rust_analyzer::main_loop::<impl rust_analyzer::global_state::GlobalState>::run
  11: rust_analyzer::main_loop::main_loop
  12: rust_analyzer::run_server
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Start at crates/base-db/src/lib.rs:133:14 and trace the FileChange::apply path shown in the backtrace. Reproduce the problem by switching revisions while an open file no longer exists, then follow how file_source_root is fetched. Done means this scenario no longer causes the LspServer to panic.