Describe the bug
Using rewrite branch (which is working great except for this issue):
After continuing to run workflows, a server crash occurs. It's about a 25% reproducibility rate.

To Reproduce
Steps to reproduce the behavior:

1. Select a workflow
2. Fill in fields
3. Run workflow
4. Repeat steps 2-3

Expected behavior
These steps should continue to work.

Actual behavior
Eventually, the web UI becomes unresponsive (because ComfyUIMini has crashed).
See console output below.

Desktop (please complete the following information):

• OS: Windows 11
• Node.js version: v23.1.0
• App version: rewrite branch
• ComfyUI version: 0.3.66

Additional context
ComfyUIMini front-end running on Firefox mobile app.

Windows 11 ComfyUIMini back-end console output:
[00:34:38] [OPTIONAL] Using cached generation result.
C:\Users\xxx\github\ComfyUIMini-rewrite\src\server\utils\comfyAPIUtils\generateImage\getOutputImages.ts:14
const historyOutputs = history[promptId].outputs;
^

TypeError: Cannot read properties of undefined (reading 'outputs')
at getOutputImages (C:\Users\xxx\github\ComfyUIMini-rewrite\src\server\utils\comfyAPIUtils\generateImage\getOutputImages.ts:14:46)
at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
at async sendCachedImages (C:\Users\xxx\github\ComfyUIMini-rewrite\src\server\utils\comfyAPIUtils\generateImage\sendCachedImages.ts:8:26)

Node.js v23.1.0