I can repro, the FIRST error is:

```
error[E0463]: can't find crate for `std`
   --> /Users/james/.cargo/registry/src/index.crates.io-6f17d22bba15001f/serde-1.0.204/src/lib.rs:172:17
    |
172 |         pub use std::*;
    |                 ^^^ can't find crate
    |
    = note: the `thumbv6m-none-eabi` target may not support the standard library


```