fix: improve error handling and add guard check to deserializeMessage

Author: Sahar Shemesh

src/shared/stdio.test.ts

@@ -33,3 +33,10 @@ test('should be reusable after clearing', () => {
     readBuffer.append(Buffer.from('\n'));
     expect(readBuffer.readMessage()).toEqual(testMessage);
 });
+
+test('should override invalid messages and return null', () => {
+    const readBuffer = new ReadBuffer();
+
+    readBuffer.append(Buffer.from('invalid message\n'));
+    expect(readBuffer.readMessage()).toBeNull();
+});

src/shared/stdio.ts

@@ -1,3 +1,4 @@
+import { ZodError } from 'zod';
 import { JSONRPCMessage, JSONRPCMessageSchema } from '../types.js';
 
 /**
@@ -30,8 +31,16 @@ export class ReadBuffer {
     }
 }
 
-export function deserializeMessage(line: string): JSONRPCMessage {
-    return JSONRPCMessageSchema.parse(JSON.parse(line));
+export function deserializeMessage(line: string): JSONRPCMessage | null {
+    try {
+        return JSONRPCMessageSchema.parse(JSON.parse(line));
+    } catch (error: unknown) {
+        // When Non JSONRPC message is received (parsing error or schema validation error), return null
+        if (error instanceof ZodError || error instanceof SyntaxError) {
+            return null;
+        }
+        throw error;
+    }
 }
 
 export function serializeMessage(message: JSONRPCMessage): string {