Anthropic LLM swallows API errors

[Jbrito6492]

Describe the bug
When the completions method is called from the AnthropicResponse object, it does not check for an error in the response. For this reason, it will return nil, and we cannot see the actual API error.

To Reproduce

1. Have 0 credits in your Anthropic account
2. Try to use the client.

I was able to reproduce this with the following lines of code (specification text is a local file in a project):

anthropic = Langchain::LLM::Anthropic.new(api_key: ENV["ANTHROPIC_API_KEY"])
chunker = Langchain::Chunker::Semantic.new(specification_text, llm: anthropic).chunks

Expected behavior
I expect to see the error I am getting from the API so I can fix the issue instead of an obfuscated error.

Terminal commands & output
Commands you used and the terminal output.

Screenshots
Error from my downstream Rails app:

Actual error from setting a debugger:

The line of code that is returning nil instead of the error is highlighted below:

Desktop (please complete the following information):
Macbook Pro

• OS: [e.g. OS X, Linux, Ubuntu, Windows]
  OS X

• Ruby version [e.g. 3.1, 3.2, 3.3]
  3.2

• Langchain.rb version [e.g. 0.13.0]
  0.13.5

Additional context
Add any other context about the problem here.