Recurring error opening any rust file

[thor314]

I've run rustup update.

On opening any rust file in emacs I get error:

Suspicious state from syntax checker rust-cargo: Flycheck checker rust-cargo returned 101, but its output contained no errors: error: no library targets found in package `clap` 

Try installing a more recent version of rust-cargo, and please open a bug report if the issue persists in the latest release.  Thanks!
user-error: Minibuffer window is not active

On opening a different rust file:

Suspicious state from syntax checker rust-cargo: Flycheck checker rust-cargo returned 101, but its output contained no errors: error: no library targets found in package `fuzzer`

Try installing a more recent version of rust-cargo, and please open a bug report if the issue persists in the latest release.  Thanks!

on flycheck-verify-setup:

Syntax checkers for buffer main.rs in rust-mode:

First checker to run:

  rust-cargo
    - may enable:  yes
    - may run:     t
    - executable:  Found at /Users/thor/.cargo/bin/cargo
    - Cargo.toml:  Found
    - Crate type:  bin
    - Binary name: clap

Checkers that could run if selected:

  rust  select
    - may enable: yes
    - may run:    t
    - executable: Found at /Users/thor/.cargo/bin/rustc

  rust-clippy  select
    - may enable: yes
    - may run:    t
    - executable: Found at /Users/thor/.cargo/bin/cargo
    - Clippy:     Found
    - Cargo.toml: Found

Flycheck Mode is enabled. Use C-u C-c ! x to enable disabled checkers.

--------------------

Flycheck version: 32snapshot (package: 20200610.1809)
Emacs version:    26.3
System:           x86_64-apple-darwin18.2.0
Window system:    ns

[thor314]

Actually, unsure what happened. Can't reproduce after a restart. Cheers.