Alert email was not sent when NR instance crashed

### Current Behavior

This instance has crashed and did not recover on 20/07/24 17:25:09 (UTC + 6) - https://app.flowfuse.com/instance/3f3be290-6f82-4883-9372-d54ff81a2b0c/logs

I have FF configured to send me alerts when this happens - https://app.flowfuse.com/instance/3f3be290-6f82-4883-9372-d54ff81a2b0c/settings/alerts

I didn't get an alert - https://d.pr/i/Qr6qVe

### Expected Behavior

I should have received an email to alert me that the instance was down.

### Steps To Reproduce

I don't have a process to manually crash this instance. If we need to do that for testing that is OK as long as the instance is brought back online within 5 minutes.

### Environment

- FlowFuse version: v2.6.2-a934275-202407221426.0
- Node.js version: v18.20.4
- npm version:
- Platform/OS:
- Browser:

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate