> I wish there was some magical way that the error type could be inferred to be a union of all of the errors that can be returned.

You could use `Result<(), Box<dyn std::error::Error>` to use dynamic dispatch at runtime and allow the function to return any type that implements `std::error::Error`.

Otherwise people often use the anyhow[1] or the thiserror[2] crate to easily work with errors. They allow concise error propagation and quickly creating custom error types.

[1]: https://docs.rs/anyhow/latest/anyhow/ [2]: https://docs.rs/thiserror/latest/thiserror/