gemini image api bug

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

text 2 image should works well

### Actual Behavior

google gemini image node
using text 2 image always comes black image

### Steps to Reproduce

just use google gemini image node

### Debug Logs

```powershell
log show nothing

got prompt
Prompt executed in 7.43 seconds
```

### Other