[JS] unhandled error when generating an image with some prompts again imagen3Fast with vertexAI

[hoff]

Describe the bug
I encounter an unhandled error with some prompts when trying to generate an image. Here is the stack trace:

TypeError: Cannot read properties of undefined (reading 'map') at file:///Users/USERNAME/code/codezero/codezero-deno/node_modules/.deno/@genkit-ai+vertexai@1.0.5/node_modules/@genkit-ai/vertexai/lib/imagen.js:200:47 at Object.runMicrotasks (ext:core/01_core.js:683:26) at processTicksAndRejections (ext:deno_node/_next_tick.ts:59:10) at runNextTicks (ext:deno_node/_next_tick.ts:76:3) at eventLoopTick (ext:core/01_core.js:182:21) at async file:///Users/USERNAME/code/codezero/codezero-deno/node_modules/.deno/@genkit-ai+core@1.0.5/node_modules/@genkit-ai/core/lib/action.js:204:14 at async file:///Users/USERNAME/code/codezero/codezero-deno/node_modules/.deno/@genkit-ai+core@1.0.5/node_modules/@genkit-ai/core/lib/action.js:125:27 at async file:///Users/USERNAME/code/codezero/codezero-deno/node_modules/.deno/@genkit-ai+core@1.0.5/node_modules/@genkit-ai/core/lib/tracing/instrumentation.js:65:16 at async file:///Users/USERNAME/code/codezero/codezero-deno/node_modules/.deno/@genkit-ai+core@1.0.5/node_modules/@genkit-ai/core/lib/tracing/instrumentation.js:88:24 at async runInNewSpan (file:///Users/USERNAME/code/codezero/codezero-deno/node_modules/.deno/@genkit-ai+core@1.0.5/node_modules/@genkit-ai/core/lib/tracing/instrumentation.js:77:10)"

To Reproduce
I followed the sample code on https://firebase.google.com/docs/genkit/models#generating-media, here is the code to reproduce the error:

`const ai = genkit({
plugins: [
googleAI({ apiKey: 'XXX' }),
vertexAI({ location: 'us-central1', projectId: 'PROJECT_NAME'}),
],
model: gemini20Flash,
})

const response = await ai.generate({
model: imagen3Fast,
prompt: 'a coach',
output: { format: 'media' },
})

`

Expected behavior
I expect either the image to be generated, or an error message explaining what the error is.

Runtime (please complete the following information):

• OS: MacOS
• Version 11.7.10

** Node version

• v20.17.0

Additional context
When using a 'bad' word in the prompt, I do get a proper error message: "Image generation failed with the following error: The prompt could not be submitted. Your current safety filter threshold prohibited one or more words in this prompt. If you think this was an error, send feedback. Support codes: 78610348, 32635315"

Some prompt work perfectly fine, like "a cat playing piano", but some prompt trigger the error described, innocent prompts like "a coach" or "a yoga pose".