feat: add core-error feature (#32)

Author: mattsse

crates/rlp/Cargo.toml

@@ -36,6 +36,9 @@ derive = ["dep:alloy-rlp-derive"]
 # Enables `core::net::` implementations always instead of conditionally through `std`.
 # Requires Rust 1.77 or newer.
 core-net = []
+# Enables `core::error::Error` implementations always instead of conditionally through `std`.
+# Requires Rust 1.81 or newer.
+core-error = []
 
 arrayvec = ["dep:arrayvec"]
 

crates/rlp/src/error.rs

@@ -33,6 +33,8 @@ pub enum Error {
     Custom(&'static str),
 }
 
+#[cfg(all(feature = "core-net", not(feature = "std")))]
+impl core::error::Error for Error {}
 #[cfg(feature = "std")]
 impl std::error::Error for Error {}