feat: improved error handling in next template of cli

[CarsonRoscoe]

Description

We received a report from TBA about improving our error handling in the Next generated chatbot. We wholeheartedly agree, and this seeks to improve it.

Tests

Now, when the UI runs into an issue, the error messages propagated come from checks in anticipation of these issues, and are readable non-vague instructions on overcoming the error.

Checklist

A couple of things to include in your PR for completeness:

• Added documentation to all relevant README.md files
• Added a changelog entry

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[avidreder]

LGTM