[Docs] Chroma Plugin example throws exception on retrieve

[FriedrichWessel]

Based on the documentation for the Chroma Plugin ( https://firebase.google.com/docs/genkit/plugins/chroma )
I created a simple example script for the ChromaPlugin.

Description
The example runs fine when using devLocalndexer / Retriever, but throws an exception when running with a ChromaDB. So there seems to be a crucial information missing on the chromaDB Plugin documentation.

Environment
Hostmachine: MacOS
ChromaServer is running in a docker Container
Embedding and LLM connect to openAI

Behaviour

• I can add content to the database in the DevUI by running the flow fillDB
• calling the flow requestDB from DevUi throws an exception:

Exception

Running action `/flow/requestDB`...
{ start: { input: 'are green cars the worst ? ' } } runEnvelope
save flow state 2b7a967c-5dc9-47c7-8aef-caad1dc537e8
Fetching traces for env `dev`.
Fetching trace `43c3efc4410189f919848c36276950ff` for env `dev`.
Fetching flow state `2b7a967c-5dc9-47c7-8aef-caad1dc537e8` for env `dev`.
Fetching actions.
/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parsers/nativeEnum.js:6
    const actualKeys = Object.keys(def.values).filter((key) => {
                              ^

TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at parseNativeEnumDef (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parsers/nativeEnum.js:6:31)
    at selectParser (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parseDef.js:119:59)
    at parseDef (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parseDef.js:52:24)
    at parseArrayDef (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parsers/array.js:12:48)
    at selectParser (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parseDef.js:104:49)
    at parseDef (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parseDef.js:52:24)
    at parseOptionalDef (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parsers/optional.js:7:43)
    at selectParser (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parseDef.js:123:55)
    at parseDef (/Users/friedrich.wessel/work/AI-Taskforce/unity-firebase-genkit-template/backend/node_modules/zod-to-json-schema/dist/cjs/parseDef.js:52:24)

Script

import * as dotenv from 'dotenv'
dotenv.config()


import { configureGenkit } from '@genkit-ai/core';
import { defineFlow } from '@genkit-ai/flow';


import { gpt4o, openAI, textEmbedding3Small}  from 'genkitx-openai';
import { Document, index, retrieve } from '@genkit-ai/ai/retriever';
import { chroma, chromaIndexerRef, chromaRetrieverRef } from 'genkitx-chromadb';


import { z } from 'zod';
import { generate } from '@genkit-ai/ai';

configureGenkit({
  plugins: [
    openAI(),
    chroma([
      {
        collectionName: 'example_db',
        embedder: textEmbedding3Small,
        createCollectionIfMissing: true,
        clientParams: {
          path: "http://localhost:8000",
        }
      },
    ])
  ],
  logLevel: 'debug',
  enableTracingAndMetrics: true,
});

export const retriever = chromaRetrieverRef({
  collectionName: 'example_db',
});

export const indexer = chromaIndexerRef({
 collectionName: 'example_db',
});

export const fillDB = defineFlow(
  {
    name: 'fillDB',
    inputSchema: z.string(),
    outputSchema: z.string(),
  },
  async (data) => {
    let doc = Document.fromText(`This is test content about ${data}`);
    const documents = [doc]
    await index({ indexer: indexer, documents })
    return `Added ${data} to the DB`;
  }
);

export const requestDB = defineFlow(
  {
    name: 'requestDB',
    inputSchema: z.string(),
    outputSchema: z.string(),
  },
  async (question) => {
      let options : any =  { k : 3}
      
      const docs = await retrieve({
        retriever: retriever,
        query : question, 
        options,
      });
      
      const llmResponse = await generate( {
        model: gpt4o,
        prompt: `${question}`,
        context: docs
      });
        
      return llmResponse.text();
  }
);