llms: extract common llms errors to shared declaration

[wgeorgecook]

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This addresses the comment Travis made in this PR I previously made. It specifically extracts the ErrorIncompleteEmbedding error and the ErrorEmptyResponse error used in the files in the /llms directory.

I specifically targeted these errors because they're the ones I encountered using LangChain Go, there is still more work to be done in consolidating all of the other potentially shared errors.

[wgeorgecook]

Looks like the ci lint wasn't run before these files made it into main. I'm working on fixing them all now.

[wgeorgecook]

CI is now passing.

[wgeorgecook]

@tmc I resolved conflicts with main for this and ensured that the linter is happy in the /llms directory. Let me know if you want to take this in a different direction but I think this is a good start towards centralizing these error messages.

[tmc]

Thanks so much, this ia great to see.

[tmc]

I wonder if llms is the right place to put the errors, I don't love the new source dependency on what is already a pretty large package implies. I don't have a better suggestion. @eliben do you have an opinion here?

[wgeorgecook]

@tmc I have the same concern. It feels weird to have a root level errors package since the exported types are directly related to the LLMs. But it doesn't have to be. But it would probably also feel weird to have a root level errors package with just any and all exported errors in it. Very open to suggestions.

[eliben]

I wonder if llms is the right place to put the errors, I don't love the new source dependency on what is already a pretty large package implies. I don't have a better suggestion. @eliben do you have an opinion here?

I don't see the advantage of this approach - what's the motivation here? How are llm-unique errors going to be represented?