Fix error messaging for openui-chat example

[zahlekhan]

Describe the bug
If user runs out of credits, then response is empty rather than showing user friendly message

To Reproduce

1. Add acc with empty credits
2. Chat responsed with empty response

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Review all error cases and send user friendly message

[shogun444]

Hi @zahlekhan ,

It returns 500 status code everytime.
Screenshot device - Desktop
OS - Windows
Browser - Chrome
version - Version 148.0.7778.168 (Official Build) (64-bit)

[zahlekhan]

Hmm, let me check and get back to you

[shogun444]

I used a wrong api key for this setup.

[shogun444]

Screenshot device - Desktop
OS - Windows
Browser - Chrome
version - Version 148.0.7778.168 (Official Build) (64-bit)

I see a rate-limit exceeded message in openroutr with a status codeof 429.

but in Openui its status code 500 only.