The exception handling in ChromaAPI when working with collections seems to be incorrect

Problem:

Method ChromaApi#getCollection throws a RuntimeException with the message : "Collection [%s] does not exist" (note the correct spelling of "exist"). This seems to be not what the framework expects - the exception is expected to be catched and then processed. For instance, in the ChromaVectorStore this is certainly not an expected behavior.

What needs to be fixed:

The ChromaApi#getCollection should return null as it was, I guess, supposed to do if the chromadb collection does not exist.

Chroma version: v1.3.4

I have created a MRE repo on hte GitHub: https://github.com/mipo256/spring-ai-autopilot-podlodka. The pre-requisite is to have the docker container for chroma running (from docker compose for example).

Start in vector-stores/spring-ai-chroma-store/src/main/java/org/springframework/ai/chroma/vectorstore/ChromaApi.java at ChromaApi#getCollection, then inspect ChromaVectorStore.java where the result is handled. Reproduce the missing-collection case with Chroma v1.3.4 and the linked MRE, and verify that getCollection returns null so ChromaVectorStore can process the absent collection without an unexpected RuntimeException.