Update index.ts

[bombjackit]

Reinforced check to cpf[0] that must not be undefined

Description, Motivation, and Context

Because I had this error [error] TypeError: Cannot read property 'data' of undefined at Browser._parseListIdentityResponse (C:\Users\xxxx.node-red\node_modules\st-ethernet-ip\src\browser\index.js:89:41) at Socket. (C:\Users\xxxx.node-red\node_modules\st-ethernet-ip\src\browser\index.js:69:33) at Socket.emit (events.js:400:28) at UDP.onMessage [as onmessage] (dgram.js:931:8)

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [X] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [X] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.
• [ ] This is a work in progress, and I want some feedback (If yes, please mark it in the title -> e.g. [WIP] Some awesome PR title)

Related Issue

[SerafinTech]

I'm going to put this change in the main branch and then delete this fork since it has already been merged.