bug(ai): Error sending prompt to AI: TypeError: Cannot read properties of undefined (reading 'some')

[anisabboud]

Operating System

Windows

Environment (if applicable)

Chrome

Firebase SDK Version

11.9.1

Firebase SDK Product(s)

AI

Project Tooling

Angular

Detailed Problem Description

I ran into this error once when sending a request to Gemini 2.5 Pro via generateContentStream:

Error sending prompt to AI: TypeError: Cannot read properties of undefined (reading 'some')

firebase-js-sdk/packages/ai/src/googleai-mappers.ts

Line 179 in 86155b3

candidate.content?.parts.some(

Perhaps candidate.content?.parts.some( should be candidate.content?.parts?.some(.

Steps and code to reproduce issue

Most requests don't seem to run into this issue, but one request did.

Replacing parts.some with parts?.some in googleai-mappers.ts should resolve the issue.

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[dlarocque]

Hi @anisabboud thanks for reporting this!

This is definitely a bug. In our SDK, we expect parts to always be defined. You seem to have gotten a response where parts is undefined.

To help us test against this case, could you please share the HTTP payload you see in the Network tab in Chrome that is associated with this error? Is there a specific prompt, config, or feature you used that triggers this?

[anisabboud]

I encountered the error only once so far, so I don't have a reproduction at this point.
The model was gemini-2.5-pro, called via generateContentStream(['']) (which returns a stream of chunks).
I.e., systemInstruction was set, but user message was an empty string.

[dlarocque]

I encountered the error only once so far, so I don't have a reproduction at this point. The model was gemini-2.5-pro, called via generateContentStream(['']) (which returns a stream of chunks). I.e., systemInstruction was set, but user message was an empty string.

Thanks for sharing- please share a payload that reproduces this if you run into this again. I can't seem to reproduce this either using an empty string as the prompt.