Return errors instead of panicking in soroban-spec-rust

[leighmcculloch]

What

Convert all code-generation functions in soroban-spec-rust (generate_struct, generate_union, generate_enum, generate_error_enum, generate_event, generate_function, and their _with_options variants) from infallible to fallible, returning GenerateError. Propagate GenerateError up through generate_from_wasm_with_options and other fns.

Why

The generator panicked on Wasm contracts with invalid UTF-8 bytes or non-identifier strings in spec entry names. Existing TODOs in the source acknowledged this.

Close #1765

Targeting

v26

[Copilot]

Pull request overview

This PR updates the soroban-spec-rust code generator to stop panicking on malformed contract specs (e.g., invalid UTF-8 or invalid Rust identifiers) by making the generation APIs fallible and returning a new GenerateError, propagating failures up through the public entrypoints.

Changes:

• Introduce GenerateError and convert spec-to-Rust generation functions (generate_* and *_with_options) to return Result<_, GenerateError> instead of panicking.
• Add syn_ext::str_to_ident to validate/parse identifiers and map invalid UTF-8 / invalid idents into GenerateError.
• Propagate generation failures up through generate_from_wasm_with_options via a new GenerateFromFileError::Generate(...) variant and add tests for invalid UTF-8/ident cases.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
soroban-spec-rust/src/types.rs	Introduces GenerateError, converts type/event generators to Result, and adds tests for invalid UTF-8/ident inputs.
soroban-spec-rust/src/trait.rs	Converts trait/function generation to Result and uses str_to_ident + fallible type generation.
soroban-spec-rust/src/syn_ext.rs	New helper module to safely convert spec strings/symbols into proc_macro2::Ident.
soroban-spec-rust/src/lib.rs	Makes top-level generation APIs fallible and maps generation errors into GenerateFromFileError.