add custom signer proxy

crates/browser-signer-proxy/src/error.rs

@@ -0,0 +1,51 @@
+// Copyright (c) 2022-2023 Yuki Kishimoto
+// Copyright (c) 2023-2025 Rust Nostr Developers
+// Distributed under the MIT software license
+
+//! Error types for the browser signer proxy.
+
+opaquerr::define_kind! {
+    /// Nostr browser signer proxy error kind.
+    pub ErrorKind {
+        /// Nostr protocol error.
+        Protocol => "nostr protocol error",
+        /// I/O error.
+        IO => "I/O error",
+        /// JSON error.
+        Json => "JSON error",
+        /// The operation timed out.
+        Timeout => "timeout",
+        /// The operation cannot be completed in the current state.
+        State => "invalid state",
+        /// Anything not covered by the stable categories above.
+        Other => "other error",
+    }
+}
+
+opaquerr::define_error! {
+    /// Nostr browser signer proxy error.
+    pub Error(ErrorKind)
+
+    from {
+        nostr::error::Error => ErrorKind::Protocol,
+        std::io::Error => ErrorKind::IO,
+        serde_json::Error => ErrorKind::Json,
+    }
+}
+
+impl Error {
+    pub(crate) fn generic<S>(message: S) -> Self
+    where
+        S: Into<String>,
+    {
+        Self::new(ErrorKind::Other, message.into())
+    }
+
+    pub(crate) fn timeout() -> Self {
+        Self::simple(ErrorKind::Timeout)
+    }
+
+    pub(crate) fn shutdown() -> Self {
+        Self::with_static_message(ErrorKind::State, "server is shutdown")
+    }
+}