fix(middleware-serde): handle unwritable error message

.changeset/brave-trees-fry.md

@@ -0,0 +1,5 @@
+---
+"@smithy/middleware-serde": patch
+---
+
+handle unwritable error.message field

packages/middleware-serde/src/deserializerMiddleware.spec.ts

@@ -99,4 +99,44 @@ describe("deserializerMiddleware", () => {
       expect(e.$response.body).toEqual("oh no");
     }
   });
+
+  it("handles unwritable error.message", async () => {
+    const exception = Object.assign({}, mockNextResponse.response, {
+      $response: {
+        body: "",
+      },
+      $responseBodyText: "oh no",
+    });
+
+    Object.defineProperty(exception, "message", {
+      set() {
+        throw new Error("may not call setter");
+      },
+      get() {
+        return "MockException";
+      },
+    });
+
+    const sink = vi.fn();
+
+    mockDeserializer.mockReset();
+    mockDeserializer.mockRejectedValueOnce(exception);
+    try {
+      await deserializerMiddleware(mockOptions, mockDeserializer)(mockNext, {
+        logger: {
+          debug: sink,
+          info: sink,
+          warn: sink,
+          error: sink,
+        },
+      })(mockArgs);
+      fail("DeserializerMiddleware should throw");
+    } catch (e) {
+      expect(sink).toHaveBeenCalledWith(
+        `Deserialization error: to see the raw response, inspect the hidden field {error}.$response on this object.`
+      );
+      expect(e.message).toEqual("MockException");
+      expect(e.$response.body).toEqual("oh no");
+    }
+  });
 });

packages/middleware-serde/src/deserializerMiddleware.ts

@@ -3,6 +3,7 @@ import {
   DeserializeHandlerArguments,
   DeserializeHandlerOutput,
   DeserializeMiddleware,
+  HandlerExecutionContext,
   ResponseDeserializer,
   SerdeContext,
   SerdeFunctions,
@@ -16,7 +17,7 @@ export const deserializerMiddleware =
     options: SerdeFunctions,
     deserializer: ResponseDeserializer<any, any, CommandSerdeContext>
   ): DeserializeMiddleware<Input, Output> =>
-  (next: DeserializeHandler<Input, Output>): DeserializeHandler<Input, Output> =>
+  (next: DeserializeHandler<Input, Output>, context: HandlerExecutionContext): DeserializeHandler<Input, Output> =>
   async (args: DeserializeHandlerArguments<Input>): Promise<DeserializeHandlerOutput<Output>> => {
     const { response } = await next(args);
     try {
@@ -41,7 +42,16 @@ export const deserializerMiddleware =
       if (!("$metadata" in error)) {
         // only apply this to non-ServiceException.
         const hint = `Deserialization error: to see the raw response, inspect the hidden field {error}.$response on this object.`;
-        error.message += "\n  " + hint;
+        try {
+          error.message += "\n  " + hint;
+        } catch (e) {
+          // Error with an unwritable message (strict mode getter with no setter).
+          if (!context.logger || context.logger?.constructor?.name === "NoOpLogger") {
+            console.warn(hint);
+          } else {
+            context.logger?.warn?.(hint);
+          }
+        }
 
         if (typeof error.$responseBodyText !== "undefined") {
           // if $responseBodyText was collected by the error parser, assign it to