Summary

This PR fixes a Denial of Service (DoS) crash in the TCP Request / TCP Out nodes that occurs when a message's payload is mutated to an unsupported type (such as a number or object) after it has been enqueued but before it is written to the socket.

Node.js's internal socket.write() throws a synchronous TypeError when it receives an invalid argument type. Because this write operation runs asynchronously inside the network connection callback or event emitter context, the exception goes uncaught, causing Node-RED to crash.

Changes

• Strict Validation in 31-tcpin.js: Added validation to verify that event.msg.payload is either a string, a Buffer, or a Uint8Array before invoking .write(). If invalid, node.error() is called to log the issue safely.
• Robust Exception Handling: Wrapped the .write() call in a try/catch block to protect against any unexpected socket-level write exceptions.
• Leak Prevention: Kept the vital event.nodeDone() call intact to ensure Node-RED's message tracking lifecycle completes correctly under both valid and invalid payload branches.
• Regression Unit Test in 31-tcprequest_spec.js: Added a test case that replicates the asynchronous mutation of payload to a number, confirming that it is safely rejected and logged as a node error without crashing Node-RED.

Verification

Verified locally by running the Mocha test suite:
npx mocha test/nodes/core/network/31-tcprequest_spec.js
Result: All 17 tests passed successfully.