notion install yarn fails to save the platform.toml file

[mikrostew]

Repro

When I run notion install yarn <version> (on current master) it's panicking and clearing the platform.toml file:

$ notion install node 11

$ cat ~/.notion/tools/user/platform.toml
[node]
runtime = '11.4.0'
npm = '6.4.1'

$ notion install yarn 1.9.2
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: ValueAfterTable', libcore/result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.

$ cat ~/.notion/tools/user/platform.toml

Investigation

Looks like it's failing on Toolchain::save

$ NOTION_DEV=1 RUST_BACKTRACE=1 notion install yarn 1.9.2
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: ValueAfterTable', libcore/result.rs:1009:5
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: std::panicking::rust_panic_with_hook
   5: std::panicking::continue_panic_fmt
   6: rust_begin_unwind
   7: core::panicking::panic_fmt
   8: core::result::unwrap_failed
   9: notion_core::toolchain::Toolchain::save
  10: notion_core::toolchain::Toolchain::set_active_yarn
  11: notion_core::session::Session::install_yarn
  12: <notion::command::install::Install as notion::command::Command>::run
  13: notion::command::Command::go
  14: notion::main
  15: std::rt::lang_start::{{closure}}
  16: std::panicking::try::do_call
  17: __rust_maybe_catch_panic
  18: std::rt::lang_start_internal
  19: main

The only line in save() that calls .unwrap() is this one (line 84 in notion-core/src/toolchain/mod.rs):

let src = toml::to_string_pretty(&platform.to_serial()).unwrap();

So that looks like an issue with platform.to_serial()

[mikrostew]

Turns out that TOML is very picky. From https://docs.rs/toml/0.4.10/toml/ser/index.html:

Note that the TOML format has a restriction that if a table itself contains tables, all keys with non-table values must be emitted first. This is typically easy to ensure happens when you're defining a struct as you can reorder the fields manually,...

So that's all I had to do is re-order the fields so that yarn comes first, because it is a non-table value (a String)