Frequent error when working in lib.rs

[abrassel]

thread '' panicked at 'called Option::unwrap() on a None value', crates/ra_syntax/src/ast/make.rs:303:16
stack backtrace:
0: backtrace::backtrace::libunwind::trace
at /cargo/registry/src/gb.xjqchip.workers.dev-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
1: backtrace::backtrace::trace_unsynchronized
at /cargo/registry/src/gb.xjqchip.workers.dev-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: core::panicking::panic_fmt
at src/libcore/panicking.rs:85
13: core::panicking::panic
at src/libcore/panicking.rs:52
14: ra_syntax::ast::make::ast_from_text
15: ra_syntax::ast::make::path_unqualified
16: ra_syntax::ast::edit::::split_prefix::split_path_prefix
17: ra_syntax::ast::edit::::split_prefix
18: ra_assists::handlers::merge_imports::try_merge_trees
19: <core::iter::adapters::Copied as core::iter::traits::iterator::Iterator>::try_fold
20: ra_assists::handlers::merge_imports::merge_imports
21: <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::next
22: <alloc::vec::Vec as alloc::vec::SpecExtend<T,I>>::from_iter
23: ra_assists::resolved_assists
24: ra_ide::assists::assists
25: std::panicking::try::do_call
26: __rust_maybe_catch_panic
at src/libpanic_unwind/lib.rs:86
27: ra_db::CheckCanceled::catch_canceled
28: ra_ide::Analysis::assists
29: rust_analyzer::main_loop::handlers::handle_code_action
30: ::call_box
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose backtrace.

[bjorn3]

On what project does this happen?

[edwin0cheng]

Minimal reproduction :

use crate:::<|>::self;

By inserting : in the cursor position repeatedly.