"failed fetching toolchain version" in VScode, with Mise

[ELLIOTTCABLE]

So, I've got Rust 1.87 installed via rustup (… via mise, although in this case, I don't think that's as relevant as it would normally be; recent versions of mise "just" invoke rustup, and Rust appears to be installed in the normal location.)

The statusbar in VScode is reporting "Failed to load workspaces."; and the output pane reports:

2025-05-20T14:49:12.89465-05:00 ERROR failed fetching toolchain version for ManifestPath
   { file: AbsPathBuf("/Users/ec/Sync/Code/twag/Cargo.toml") } workspace
   e=Failed to query rust toolchain version via
   `cd "/Users/ec/Sync/Code/twag" && "cargo" "--version"`,
   is your toolchain setup correctly?
2025-05-20T14:49:12.898494-05:00 ERROR failed fetching data layout for ManifestPath
   { file: AbsPathBuf("/Users/ec/Sync/Code/twag/Cargo.toml") } workspace
   e=unable to fetch target-data-layout via
   `cd "/Users/ec/Sync/Code/twag" && RUSTC_BOOTSTRAP="1" "rustc" "-Z" "unstable-options" "--print" "target-spec-json"`
2025-05-20T14:49:12.915276-05:00 ERROR FetchWorkspaceError: rust-analyzer failed to load workspace:
   Failed to load the project at /Users/ec/Sync/Code/twag/Cargo.toml:
   Failed to read Cargo metadata from Cargo.toml file /Users/ec/Sync/Code/twag/Cargo.toml, None:
   Failed to run
   `cd "/Users/ec/Sync/Code/twag" && "cargo" "metadata" "--format-version" "1" "--manifest-path" "/Users/ec/Sync/Code/twag/Cargo.toml"`:
   No such file or directory (os error 2)

It gets stranger, though, if I explicitly set the $PATH for the server in VScode's settings …

"rust-analyzer.server.extraEnv": { "PATH": "/Users/ec/.cargo/bin:$PATH" },

… because the error-messages now include an explicit path that produces the same error-message:

2025-05-20T14:49:12.89465-05:00 ERROR failed fetching toolchain version for ManifestPath
   { file: AbsPathBuf("/Users/ec/Sync/Code/twag/Cargo.toml") } workspace
   e=Failed to query rust toolchain version via
   `cd "/Users/ec/Sync/Code/twag" && "/Users/ec/.cargo/bin/cargo" "--version"`,
   is your toolchain setup correctly?

If I open a terminal with no environment with env - bash, that command runs just fine:

$ env - dash
$ env
PWD=/Users/ec

$ cd "/Users/ec/Sync/Code/twag" && "/Users/ec/.cargo/bin/cargo" "--version"
cargo 1.87.0 (99624be96 2025-05-06)

How have I screwed up my VScode / rust-analyzer installation such that this occurs?

Versions and paths:

$ env - dash

$ env
PWD=/Users/ec

$ /Users/ec/.cargo/bin/rustup --version
rustup 1.28.2 (e4f3ad6f8 2025-04-28)

$ /Users/ec/.cargo/bin/rustc --version 
rustc 1.87.0 (17067e9ac 2025-05-09)

$ /Users/ec/.cargo/bin/cargo --version 
cargo 1.87.0 (99624be96 2025-05-06)

Rust analyzer:

rust-analyzer version: 0.3.2466-standalone (e464ff8c75 2025-05-18)
[/Users/ec/.vscode/extensions/rust-lang.rust-analyzer-0.3.2466-darwin-x64/server/rust-analyzer]

[ELLIOTTCABLE]

… restarting VScode fully fixed the problem. Not restarting the LSP server; not reloading extensions (my usual go-tos), but quitting the (macOS) program entirely, closing all of the half-dozen long-lived workspaces on my machine.

How strange. I've never had to do that intentionally before.