rust-error-handling

Rust error handling in Leptos and Axum apps is managed by defining a centralized AppError enum using thiserror, implementing IntoResponse to map errors to HTTP status codes, and using FromServerFnError to safely cross the client-server boundary.

Missing From impls and ? operator compatibility errors are resolved by adding #[from] attributes to your thiserror enum variants, enabling automatic conversion between underlying error types like sqlx::Error and your custom domain AppError.

Preventing internal error leakage in Axum HTTP responses requires implementing the IntoResponse trait for your AppError enum to map domain errors to generic, safe HTTP status codes like 500, 404, or 422 without exposing internal stack traces.

Propagating typed errors across Rust server functions involves implementing the FromServerFnError trait for your AppError enum, ensuring that domain errors are safely mapped and transmitted across the server function boundary to the Leptos client.

Use thiserror for library and domain code to define specific, typed AppError variants with compile-time checks, and use anyhow for application-level code where you need simple error aggregation without designing a dedicated error enum.

Mapping Rust application errors to HTTP status codes like 404 and 422 is done by implementing the IntoResponse trait for your AppError enum, defining a match block that converts each typed error variant into the appropriate Axum HTTP response.