[BUG] Language Server Crash on trivial edits to new project

[lilyball]

Describe the bug
I created a new project with cargo new foo, opened it in Nova, and began editing the main.rs file. And the language server keeps crashing on every edit. I restart it, it looks fine, I edit the file, crash.

Crash log

Rust Analyzer[11:13:31.012000] waiting for cargo metadata or cargo check
Rust Analyzer[11:13:31.705000] waiting for cargo metadata or cargo check
Rust Analyzer[11:13:31.754000] waiting for cargo metadata or cargo check
Rust Analyzer[11:13:32.545000] content modified
Rust Analyzer[11:13:33.574000] canceled by client
Rust Analyzer[11:13:36.553000] canceled by client
Rust Analyzer[11:13:36.670000] canceled by client
Rust Analyzer[11:13:45.842000] Panic context:
Rust Analyzer[11:13:45.842000] > 
Rust Analyzer[11:13:45.842000] version: ed4b312fa 2021-10-11 stable
Rust Analyzer[11:13:45.842000] request: textDocument/codeAction CodeActionParams {
Rust Analyzer[11:13:45.842000]     text_document: TextDocumentIdentifier {
Rust Analyzer[11:13:45.842000]         uri: Url {
Rust Analyzer[11:13:45.842000]             scheme: "file",
Rust Analyzer[11:13:45.842000]             cannot_be_a_base: false,
Rust Analyzer[11:13:45.842000]             username: "",
Rust Analyzer[11:13:45.842000]             password: None,
Rust Analyzer[11:13:45.842000]             host: None,
Rust Analyzer[11:13:45.842000]             port: None,
Rust Analyzer[11:13:45.842000]             path: "/Volumes/Macintosh%20HD/Users/lily/Desktop/foo/src/main.rs",
Rust Analyzer[11:13:45.842000]             query: None,
Rust Analyzer[11:13:45.842000]             fragment: None,
Rust Analyzer[11:13:45.842000]         },
Rust Analyzer[11:13:45.842000]     },
Rust Analyzer[11:13:45.842000]     range: Range {
Rust Analyzer[11:13:45.842000]         start: Position {
Rust Analyzer[11:13:45.842000]             line: 5,
Rust Analyzer[11:13:45.842000]             character: 0,
Rust Analyzer[11:13:45.842000]         },
Rust Analyzer[11:13:45.842000]         end: Position {
Rust Analyzer[11:13:45.842000]             line: 5,
Rust Analyzer[11:13:45.842000]             character: 0,
Rust Analyzer[11:13:45.842000]         },
Rust Analyzer[11:13:45.842000]     },
Rust Analyzer[11:13:45.842000]     context: CodeActionContext {
Rust Analyzer[11:13:45.842000]         diagnostics: [],
Rust Analyzer[11:13:45.842000]         only: None,
Rust Analyzer[11:13:45.842000]     },
Rust Analyzer[11:13:45.842000]     work_done_progress_params: WorkDoneProgressParams {
Rust Analyzer[11:13:45.842000]         work_done_token: None,
Rust Analyzer[11:13:45.842000]     },
Rust Analyzer[11:13:45.842000]     partial_result_params: PartialResultParams {
Rust Analyzer[11:13:45.842000]         partial_result_token: None,
Rust Analyzer[11:13:45.842000]     },
Rust Analyzer[11:13:45.842000] }
Rust Analyzer[11:13:45.842000] 
Rust Analyzer[11:13:45.842000] thread '<unnamed>' panicked at 'index out of bounds: the len is 5 but the index is 5', crates/ide_db/src/line_index.rs:106:9
Rust Analyzer[11:13:45.842000] stack backtrace:
Rust Analyzer[11:13:45.843000] Panic context:
Rust Analyzer[11:13:45.843000] > 
Rust Analyzer[11:13:45.843000] version: ed4b312fa 2021-10-11 stable
Rust Analyzer[11:13:45.843000] request: textDocument/completion CompletionParams {
Rust Analyzer[11:13:45.843000]     text_document_position: TextDocumentPositionParams {
Rust Analyzer[11:13:45.843000]         text_document: TextDocumentIdentifier {
Rust Analyzer[11:13:45.843000]             uri: Url {
Rust Analyzer[11:13:45.843000]                 scheme: "file",
Rust Analyzer[11:13:45.843000]                 cannot_be_a_base: false,
Rust Analyzer[11:13:45.843000]                 username: "",
Rust Analyzer[11:13:45.843000]                 password: None,
Rust Analyzer[11:13:45.843000]                 host: None,
Rust Analyzer[11:13:45.843000]                 port: None,
Rust Analyzer[11:13:45.843000]                 path: "/Volumes/Macintosh%20HD/Users/lily/Desktop/foo/src/main.rs",
Rust Analyzer[11:13:45.843000]                 query: None,
Rust Analyzer[11:13:45.843000]                 fragment: None,
Rust Analyzer[11:13:45.843000]             },
Rust Analyzer[11:13:45.843000]         },
Rust Analyzer[11:13:45.843000]         position: Position {
Rust Analyzer[11:13:45.843000]             line: 5,
Rust Analyzer[11:13:45.843000]             character: 0,
Rust Analyzer[11:13:45.843000]         },
Rust Analyzer[11:13:45.843000]     },
Rust Analyzer[11:13:45.843000]     work_done_progress_params: WorkDoneProgressParams {
Rust Analyzer[11:13:45.843000]         work_done_token: None,
Rust Analyzer[11:13:45.843000]     },
Rust Analyzer[11:13:45.843000]     partial_result_params: PartialResultParams {
Rust Analyzer[11:13:45.843000]         partial_result_token: None,
Rust Analyzer[11:13:45.843000]     },
Rust Analyzer[11:13:45.843000]     context: Some(
Rust Analyzer[11:13:45.843000]         CompletionContext {
Rust Analyzer[11:13:45.843000]             trigger_kind: TriggerCharacter,
Rust Analyzer[11:13:45.843000]             trigger_character: Some(
Rust Analyzer[11:13:45.843000]                 "f",
Rust Analyzer[11:13:45.843000]             ),
Rust Analyzer[11:13:45.843000]         },
Rust Analyzer[11:13:45.843000]     ),
Rust Analyzer[11:13:45.843000] }
Rust Analyzer[11:13:45.843000] 
Rust Analyzer[11:13:45.843000] thread '<unnamed>' panicked at 'index out of bounds: the len is 5 but the index is 5', crates/ide_db/src/line_index.rs:106:9
Rust Analyzer[11:13:45.854000]    0: _rust_begin_unwind
Rust Analyzer[11:13:45.854000]    1: core::panicking::panic_fmt
Rust Analyzer[11:13:45.854000]    2: core::panicking::panic_bounds_check
Rust Analyzer[11:13:45.854000]    3: rust_analyzer::from_proto::text_range
Rust Analyzer[11:13:45.854000]    4: rust_analyzer::from_proto::file_range
Rust Analyzer[11:13:45.854000]    5: rust_analyzer::handlers::handle_code_action
Rust Analyzer[11:13:45.854000]    6: std::panicking::try
Rust Analyzer[11:13:45.854000]    7: <F as threadpool::FnBox>::call_box
Rust Analyzer[11:13:45.854000] note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Rust Analyzer[11:13:45.854000] stack backtrace:
Rust Analyzer[11:13:45.854000]    0: _rust_begin_unwind
Rust Analyzer[11:13:45.854000]    1: core::panicking::panic_fmt
Rust Analyzer[11:13:45.854000]    2: core::panicking::panic_bounds_check
Rust Analyzer[11:13:45.854000]    3: rust_analyzer::from_proto::file_position
Rust Analyzer[11:13:45.854000]    4: rust_analyzer::handlers::handle_completion
Rust Analyzer[11:13:45.854000]    5: std::panicking::try
Rust Analyzer[11:13:45.854000]    6: <F as threadpool::FnBox>::call_box
Rust Analyzer[11:13:45.854000] note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Rust Analyzer[11:13:45.855000] server panicked: index out of bounds: the len is 5 but the index is 5
Rust Analyzer[11:13:45.855000] server panicked: index out of bounds: the len is 5 but the index is 5
Rust Analyzer[11:13:46.012000] Panic context:
Rust Analyzer[11:13:46.012000] > 
Rust Analyzer[11:13:46.012000] version: ed4b312fa 2021-10-11 stable
Rust Analyzer[11:13:46.012000] notification: textDocument/didChange
Rust Analyzer[11:13:46.012000] 
Rust Analyzer[11:13:46.012000] thread 'main' panicked at 'index out of bounds: the len is 5 but the index is 5', crates/ide_db/src/line_index.rs:106:9
Rust Analyzer[11:13:46.012000] stack backtrace:
Rust Analyzer[11:13:46.012000]    0: _rust_begin_unwind
Rust Analyzer[11:13:46.012000]    1: core::panicking::panic_fmt
Rust Analyzer[11:13:46.012000]    2: core::panicking::panic_bounds_check
Rust Analyzer[11:13:46.012000]    3: rust_analyzer::from_proto::text_range
Rust Analyzer[11:13:46.012000]    4: rust_analyzer::lsp_utils::apply_document_changes
Rust Analyzer[11:13:46.012000]    5: core::ops::function::FnOnce::call_once
Rust Analyzer[11:13:46.012000]    6: rust_analyzer::dispatch::NotificationDispatcher::on
Rust Analyzer[11:13:46.012000]    7: rust_analyzer::main_loop::<impl rust_analyzer::global_state::GlobalState>::handle_event
Rust Analyzer[11:13:46.012000]    8: rust_analyzer::main_loop::<impl rust_analyzer::global_state::GlobalState>::run
Rust Analyzer[11:13:46.012000]    9: rust_analyzer::main_loop::main_loop
Rust Analyzer[11:13:46.012000]   10: rust_analyzer::try_main
Rust Analyzer[11:13:46.012000]   11: rust_analyzer::main
Rust Analyzer[11:13:46.012000] note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Rust Analyzer[11:13:46.012000] thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: "SendError(..)"', /Users/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/lsp-server-0.5.2/src/stdio.rs:29:37
Rust Analyzer[11:13:46.012000] stack backtrace:
Rust Analyzer[11:13:46.012000]    0: _rust_begin_unwind
Rust Analyzer[11:13:46.012000]    1: core::panicking::panic_fmt
Rust Analyzer[11:13:46.012000]    2: core::result::unwrap_failed
Rust Analyzer[11:13:46.012000] note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Rust[11:13:46.329000] Error: Task “rust” exited with a non-zero exit status: 101.

To Reproduce
Steps to reproduce the behavior:

1. cargo new foo in the terminal
2. Drag the new foo folder into Nova
3. Open src/main.rs
4. Edit the file

Additional information
I haven't attempted to reproduce this with a fresh project.

In addition, after collecting that log, I cleared the console, opted to Restart Server, and then noticed that every cursor movement would log another panic (but would not tell me that the language server crashed). Hitting Save informed me of the crash again. I hit Restart Server again, and got

Rust Analyzer[11:18:54.454000] waiting for cargo metadata or cargo check
Rust Analyzer[11:18:56.002000] content modified

At this point every time I moved the cursor I'd get a line like

Rust Analyzer[11:18:56.878000] canceled by client

I hit Save again and this time it finally showed

Rust[11:19:05.080000]     Checking foo v0.1.0 (/Users/lily/Desktop/foo)
Rust[11:19:05.237000]     Finished dev [unoptimized + debuginfo] target(s) in 0.15s

Once I saw that, moving the cursor no longer logged anything, and I was able to make a trivial edit without logging too.

However, while writing up this report, after having left it alone for a while, I went back to Nova and inserted a single space at the end of the file, at which point the language server promptly crashed again.

Versions (please complete the following information):

• macOS: macOS 11.6 (20G165)
• Processor: Intel
• Nova 7.5
• Extension Version 1.0.3

[lilyball]

Playing some more, after a save and more of the canceled by client lines, waiting long enough will cause it to stop logging those. At this point I could make a trivial edit inside of my fn main() (inserting a space), or in between my struct Foo { … } and fn main() items, but once again, inserting a single space at the end of the file crashed the language server.

[lilyball]

It looks like the "index out of bounds" index is in fact the last line in the file.

Similarly, I deleted that blank line, at which point mere cursor interactions on what was now the last line caused panics.

So it looks like the core problem here is any editor interaction involving the last line of the file is panicking.

[kilbd]

Thank you for this detailed bug report!

You've definitely hit on an issue with the last line causing problems like "out of bounds" error with Rust Analyzer. I think this issue sounds like a core Nova bug I've heard of elsewhere, so it's not something I can fix. Other extensions have logged the same issue, and it's been mentioned multiple times in their extension developer forum. Panic is aware of the issue, but hasn't stated if a fix is imminent.

I've noticed the canceled by client log a lot too, so I need to dig into what's causing it. It did seem mostly benign (like maybe from mousing out of an identifier while it was in the middle of providing hover info), but I wanted to be sure when I had time.

[kilbd]

Like Code Actions, Panic appears to have fixed this issue in version 9 which was released today. Let me know if anyone still has this issue.