Impove derive macro error message

[constfold]

Currently when an error happend in deive macro it will just panic, we should use syn::Error::to_compile_error() instead.
For example, an invalid attribute give this message:

error: proc-macro derive panicked
 --> src\main.rs:3:10
  |
3 | #[derive(DekuRead)]
  |          ^^^^^^^^
  |
  = help: message: called `Result::unwrap()` on an `Err` value: Error { kind: UnknownField(ErrorUnknownField { name: "id", did_you_mean: None }), locations: ["b"], span: Some(#0 bytes(79..86)) }

A better message could be:

error: unknown deku field attribute `id`
 --> src\main.rs:3:10
|
7| #[deku(id = "")]
|         ^^

[sharksforarms]

Made a commit to master: d7d5f7d

Let me know if that's what you were thinking! Changes the unwrap panic to compile error

[constfold]

@sharksforarms looks good! and FYI there still are a few panics in Deku*Receiver like

deku/deku-derive/src/lib.rs

Line 64 in d7d5f7d

panic!("`id_*` attributes only supported on enum")

deku/deku-derive/src/lib.rs

Line 69 in d7d5f7d

panic!("`id_type` must be specified with `id_bits` or `id_bytes`");

Maybe hard to convert?

[sharksforarms]

@sharksforarms looks good! and FYI there still are a few panics in Deku*Receiver like

deku/deku-derive/src/lib.rs

Line 64 in d7d5f7d

panic!("`id_*` attributes only supported on enum")

deku/deku-derive/src/lib.rs

Line 69 in d7d5f7d

panic!("`id_type` must be specified with `id_bits` or `id_bytes`");

Maybe hard to convert?

Yes. Not exactly sure how to convert these. I'm using darling's map = in order to validate... maybe there's a better way.

[sharksforarms]

Addressed in #61