does `PlatformId::to_str` need to return an error?

[flihp]

This is a tuple struct and the data is not public so as long as we validate inputs to the constructors the to_str function shouldn't need validation.

[flihp]

Took a look at this for a bit today and realized that this type is serialized and sent back and forth between the RoT & the mfg station. I guess this means that we can't rely on the constructor to do the validation ... unless we can convince serde / hubpack to use a TryFrom to do the deserialization. Serde will let us do this with #[serde(try_from = "...")] a-la https://serde.rs/container-attrs.html#try_from but using the existing TryFrom<&[u8]> produces hubpack::error::Error::NotSupported. We may be able to work around this by implementing a new TryFrom<[u8; PLATFORM_ID_MAX_LEN]>?

[flihp]

Implementing TryFrom<[u8; PLATFORM_ID_MAX_LEN]> did the trick. There was some weirdness w/r/t satisfying the constraints from the serde try_from attribute under no_std but a custom impl core::fmt::Display was enough to get this working.