feat: add wasm-rust sdk with say-hello simple extension (#350)

plugins/wasm-rust/src/error.rs

@@ -0,0 +1,39 @@
+// Copyright (c) 2023 Alibaba Group Holding Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::error::Error;
+use std::fmt::{Display, Formatter};
+
+#[derive(Debug, Default)]
+pub struct WasmRustError {
+    message: String,
+}
+
+impl WasmRustError {
+    pub const fn new(message: String) -> Self {
+        WasmRustError { message }
+    }
+}
+
+impl Display for WasmRustError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.message)
+    }
+}
+
+impl Error for WasmRustError {
+    fn description(&self) -> &str {
+        &self.message
+    }
+}